diff --git a/packages/react-relay/multi-actor/__tests__/ActorChange-test.js b/packages/react-relay/multi-actor/__tests__/ActorChange-test.js
index 55057f7a47573..07f120bffb576 100644
--- a/packages/react-relay/multi-actor/__tests__/ActorChange-test.js
+++ b/packages/react-relay/multi-actor/__tests__/ActorChange-test.js
@@ -131,7 +131,7 @@ type Props = $ReadOnly<{
 
 function ActorMessage(props: Props) {
   const data = useFragment(fragment, props.myFragment);
-  const [commit] = useMutation(mutation);
+  const [commit] = useMutation<$FlowFixMe>(mutation);
 
   // We're calling this hook only to verify that it won't throw.
   // `useRelayActorEnvironment` should be able to have access to `getEnvironmentForActor` function
diff --git a/packages/react-relay/relay-hooks/__tests__/FragmentResource-ClientEdges-test.js b/packages/react-relay/relay-hooks/__tests__/FragmentResource-ClientEdges-test.js
index fa3a62b663249..b8eb0883779e2 100644
--- a/packages/react-relay/relay-hooks/__tests__/FragmentResource-ClientEdges-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/FragmentResource-ClientEdges-test.js
@@ -237,7 +237,7 @@ describe('FragmentResource Client Edges behavior', () => {
     // Use our own simulation of setTimeout due to bugs in Jest's.
     // We can't mock SuspenseResource's setTimeout using Jest mocks because
     // they aren't imported from a module, so we swizzle the global one.
-    const timeouts = new Map();
+    const timeouts = new Map<number, $FlowFixMe>();
     let nextTimeoutID = 0;
     const originalSetTimeout = global.setTimeout;
     const originalClearTimeout = global.clearTimeout;
diff --git a/packages/react-relay/relay-hooks/__tests__/QueryResource-test.js b/packages/react-relay/relay-hooks/__tests__/QueryResource-test.js
index ba9bf76ffd375..a8feae198ead0 100644
--- a/packages/react-relay/relay-hooks/__tests__/QueryResource-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/QueryResource-test.js
@@ -286,7 +286,7 @@ describe('QueryResource', () => {
           let thrown = false;
           let sink;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(s => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(s => {
             networkExecute();
             sink = s;
           });
@@ -331,7 +331,7 @@ describe('QueryResource', () => {
           });
 
           const networkExecute = jest.fn();
-          const syncFetchObservable = Observable.create(sink => {
+          const syncFetchObservable = Observable.create<$FlowFixMe>(sink => {
             environment.commitPayload(queryMissingData, {
               node: {
                 __typename: 'User',
@@ -375,7 +375,7 @@ describe('QueryResource', () => {
         it('should throw error if network request errors synchronously', () => {
           let thrown = false;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(sink => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(sink => {
             networkExecute();
             sink.error(new Error('Oops'));
           });
@@ -702,7 +702,7 @@ describe('QueryResource', () => {
           let thrown = false;
           let sink;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(s => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(s => {
             networkExecute();
             sink = s;
           });
@@ -753,7 +753,7 @@ describe('QueryResource', () => {
           });
 
           const networkExecute = jest.fn();
-          const syncFetchObservable = Observable.create(sink => {
+          const syncFetchObservable = Observable.create<$FlowFixMe>(sink => {
             environment.commitPayload(queryMissingData, {
               node: {
                 __typename: 'User',
@@ -797,7 +797,7 @@ describe('QueryResource', () => {
         it('should throw error if network request errors synchronously', () => {
           let thrown = false;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(sink => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(sink => {
             networkExecute();
             sink.error(new Error('Oops'));
           });
@@ -1262,7 +1262,7 @@ describe('QueryResource', () => {
           let thrown = false;
           let sink;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(s => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(s => {
             networkExecute();
             sink = s;
           });
@@ -1306,7 +1306,7 @@ describe('QueryResource', () => {
           });
 
           const networkExecute = jest.fn();
-          const syncFetchObservable = Observable.create(sink => {
+          const syncFetchObservable = Observable.create<$FlowFixMe>(sink => {
             environment.commitPayload(queryMissingData, {
               node: {
                 __typename: 'User',
@@ -1350,7 +1350,7 @@ describe('QueryResource', () => {
         it('should throw error if network request errors synchronously', () => {
           let thrown = false;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(sink => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(sink => {
             networkExecute();
             sink.error(new Error('Oops'));
           });
@@ -1500,7 +1500,7 @@ describe('QueryResource', () => {
           let thrown = false;
           let sink;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(s => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(s => {
             networkExecute();
             sink = s;
           });
@@ -1549,7 +1549,7 @@ describe('QueryResource', () => {
           });
 
           const networkExecute = jest.fn();
-          const syncFetchObservable = Observable.create(sink => {
+          const syncFetchObservable = Observable.create<$FlowFixMe>(sink => {
             environment.commitPayload(queryMissingData, {
               node: {
                 __typename: 'User',
@@ -1593,7 +1593,7 @@ describe('QueryResource', () => {
         it('should throw error if network request errors synchronously', () => {
           let thrown = false;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(sink => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(sink => {
             networkExecute();
             sink.error(new Error('Oops'));
           });
@@ -1725,7 +1725,7 @@ describe('QueryResource', () => {
           let thrownError = false;
           let sink;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(s => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(s => {
             networkExecute();
             sink = s;
           });
@@ -1772,7 +1772,7 @@ describe('QueryResource', () => {
 
         it('should return result if network observable returns synchronously', () => {
           const networkExecute = jest.fn();
-          const syncFetchObservable = Observable.create(sink => {
+          const syncFetchObservable = Observable.create<$FlowFixMe>(sink => {
             const snapshot = environment.lookup(query.fragment);
             networkExecute();
             sink.next((snapshot: $FlowFixMe));
@@ -1810,7 +1810,7 @@ describe('QueryResource', () => {
         it('should throw error if network request errors synchronously', () => {
           let thrown = false;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(sink => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(sink => {
             networkExecute();
             const error = new Error('Oops');
             sink.error(error);
@@ -1907,7 +1907,7 @@ describe('QueryResource', () => {
           let thrownError = false;
           let sink;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(s => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(s => {
             networkExecute();
             sink = s;
           });
@@ -1954,7 +1954,7 @@ describe('QueryResource', () => {
 
         it('should return result if network observable returns synchronously', () => {
           const networkExecute = jest.fn();
-          const syncFetchObservable = Observable.create(sink => {
+          const syncFetchObservable = Observable.create<$FlowFixMe>(sink => {
             const snapshot = environment.lookup(query.fragment);
             networkExecute();
             sink.next((snapshot: $FlowFixMe));
@@ -1992,7 +1992,7 @@ describe('QueryResource', () => {
         it('should throw error if network request errors synchronously', () => {
           let thrown = false;
           const networkExecute = jest.fn();
-          const errorFetchObservable = Observable.create(sink => {
+          const errorFetchObservable = Observable.create<$FlowFixMe>(sink => {
             networkExecute();
             const error = new Error('Oops');
             sink.error(error);
diff --git a/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-test.js b/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-test.js
index 70de54598296c..2bc83dff6da5b 100644
--- a/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-test.js
@@ -85,7 +85,7 @@ describe('useBlockingPaginationFragment', () => {
     fragmentRef: mixed,
   ) {
     // $FlowFixMe[incompatible-call]
-    const {data, ...result} = useBlockingPaginationFragmentOriginal(
+    const {data, ...result} = useBlockingPaginationFragmentOriginal<any, mixed>(
       fragmentNode,
       // $FlowFixMe[incompatible-call]
       // $FlowFixMe[prop-missing]
@@ -1655,7 +1655,7 @@ describe('useBlockingPaginationFragment', () => {
         const useLoadMoreFunction = require('../useLoadMoreFunction');
         // $FlowFixMe[prop-missing]
         useLoadMoreFunction.mockImplementation((...args) =>
-          jest.requireActual('../useLoadMoreFunction')(...args),
+          jest.requireActual<any>('../useLoadMoreFunction')(...args),
         );
 
         const callback = jest.fn();
diff --git a/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js b/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js
index 988aae438aec4..6c047f031e927 100644
--- a/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js
@@ -77,7 +77,7 @@ describe('useBlockingPaginationFragment with useTransition', () => {
     ) {
       const [isPendingNext, startTransition] = useTransition();
       // $FlowFixMe[incompatible-call]
-      const {data, ...result} = useBlockingPaginationFragmentOriginal(
+      const {data, ...result} = useBlockingPaginationFragmentOriginal<any, any>(
         fragmentNode,
         // $FlowFixMe[prop-missing]
         // $FlowFixMe[incompatible-call]
diff --git a/packages/react-relay/relay-hooks/__tests__/useEntryPointLoader-test.js b/packages/react-relay/relay-hooks/__tests__/useEntryPointLoader-test.js
index d96db2c4f61d3..a00fadf5af393 100644
--- a/packages/react-relay/relay-hooks/__tests__/useEntryPointLoader-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useEntryPointLoader-test.js
@@ -73,7 +73,10 @@ beforeEach(() => {
   }) {
     renderCount = (renderCount || 0) + 1;
     [loadedEntryPoint, entryPointLoaderCallback, disposeEntryPoint] =
-      useEntryPointLoader(environmentProvider, entryPoint);
+      useEntryPointLoader<{...}, any, any, any, any, any, any>(
+        environmentProvider,
+        entryPoint,
+      );
     return null;
   };
   loadEntryPoint.mockClear();
diff --git a/packages/react-relay/relay-hooks/__tests__/useFragmentNode-react-double-effects-test.js b/packages/react-relay/relay-hooks/__tests__/useFragmentNode-react-double-effects-test.js
index a3730cd29d0e7..db3bcf76c09d4 100644
--- a/packages/react-relay/relay-hooks/__tests__/useFragmentNode-react-double-effects-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useFragmentNode-react-double-effects-test.js
@@ -75,7 +75,7 @@ describe.skip('useFragmentNode-react-double-effects-test', () => {
 
     let renderLogs = [];
     const FragmentComponent = ({user}: $TEMPORARY$object<{user: mixed}>) => {
-      const {data} = useFragmentNode(gqlFragment, user, 'TestComponent');
+      const {data} = useFragmentNode<any>(gqlFragment, user, 'TestComponent');
       useEffect(() => {
         renderLogs.push(`commit: ${data.name}`);
         return () => {
diff --git a/packages/react-relay/relay-hooks/__tests__/useFragmentNode-required-test.js b/packages/react-relay/relay-hooks/__tests__/useFragmentNode-required-test.js
index bcfa1a06f085e..6cb2e355a88b4 100644
--- a/packages/react-relay/relay-hooks/__tests__/useFragmentNode-required-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useFragmentNode-required-test.js
@@ -43,7 +43,7 @@ function useFragmentNode(
     __isWithinUnmatchedTypeRefinement: boolean,
   }>,
 ) {
-  const result = useFragmentNodeOriginal(
+  const result = useFragmentNodeOriginal<any>(
     fragmentNode,
     fragmentRef,
     'TestDisplayName',
diff --git a/packages/react-relay/relay-hooks/__tests__/useFragmentNode-test.js b/packages/react-relay/relay-hooks/__tests__/useFragmentNode-test.js
index db42d1155be31..3a982b9857161 100644
--- a/packages/react-relay/relay-hooks/__tests__/useFragmentNode-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useFragmentNode-test.js
@@ -168,7 +168,7 @@ describe.each([
           >,
       fragmentRef: any,
     ) {
-      const result = useFragmentNodeOriginal(
+      const result = useFragmentNodeOriginal<any>(
         fragmentNode,
         fragmentRef,
         'TestDisplayName',
diff --git a/packages/react-relay/relay-hooks/__tests__/useMutation-fast-refresh-test.js b/packages/react-relay/relay-hooks/__tests__/useMutation-fast-refresh-test.js
index 4b418649988f4..deef29757497f 100644
--- a/packages/react-relay/relay-hooks/__tests__/useMutation-fast-refresh-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useMutation-fast-refresh-test.js
@@ -82,7 +82,9 @@ describe('useLazyLoadQueryNode', () => {
     ReactRefreshRuntime.injectIntoGlobalHook(global);
     let commit;
     const V1 = function (props: {}) {
-      const [commitFn, isMutationInFlight] = useMutation(CommentCreateMutation);
+      const [commitFn, isMutationInFlight] = useMutation<any>(
+        CommentCreateMutation,
+      );
       commit = commitFn;
       return isInFlightFn(isMutationInFlight);
     };
@@ -116,7 +118,9 @@ describe('useLazyLoadQueryNode', () => {
 
     // Trigger a fast fresh
     function V2(props: any) {
-      const [commitFn, isMutationInFlight] = useMutation(CommentCreateMutation);
+      const [commitFn, isMutationInFlight] = useMutation<any>(
+        CommentCreateMutation,
+      );
       commit = commitFn;
       return isInFlightFn(isMutationInFlight);
     }
diff --git a/packages/react-relay/relay-hooks/__tests__/useMutation-test.js b/packages/react-relay/relay-hooks/__tests__/useMutation-test.js
index 47e9fa12cacf1..3e6408d414f3a 100644
--- a/packages/react-relay/relay-hooks/__tests__/useMutation-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useMutation-test.js
@@ -94,7 +94,7 @@ beforeEach(() => {
   }) {
     const [mutation, setMutationFn] = useState(initialMutation);
     setMutation = setMutationFn;
-    const [commitFn, isMutationInFlight] = useMutation(mutation);
+    const [commitFn, isMutationInFlight] = useMutation<any>(mutation);
     commit = (config: any) =>
       ReactTestRenderer.act(() => {
         disposable = commitFn(config);
diff --git a/packages/react-relay/relay-hooks/__tests__/usePaginationFragment-test.js b/packages/react-relay/relay-hooks/__tests__/usePaginationFragment-test.js
index 057ad6f1145fa..c5d53802c881e 100644
--- a/packages/react-relay/relay-hooks/__tests__/usePaginationFragment-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/usePaginationFragment-test.js
@@ -133,7 +133,7 @@ describe.each([
   }
 
   function usePaginationFragment(fragmentNode: any, fragmentRef: any) {
-    const {data, ...result} = usePaginationFragmentOriginal(
+    const {data, ...result} = usePaginationFragmentOriginal<any, any>(
       fragmentNode,
       fragmentRef,
     );
diff --git a/packages/react-relay/relay-hooks/__tests__/useRefetchableFragment-test.js b/packages/react-relay/relay-hooks/__tests__/useRefetchableFragment-test.js
index a08d1406a4646..93a39360ee82c 100644
--- a/packages/react-relay/relay-hooks/__tests__/useRefetchableFragment-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useRefetchableFragment-test.js
@@ -39,7 +39,7 @@ describe('useRefetchableFragment', () => {
   let Renderer;
 
   function useRefetchableFragment(fragmentNode: any, fragmentRef: any) {
-    const [data, refetch] = useRefetchableFragmentOriginal(
+    const [data, refetch] = useRefetchableFragmentOriginal<any, any>(
       fragmentNode,
       // $FlowFixMe[incompatible-call]
       // $FlowFixMe[prop-missing]
diff --git a/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-test.js b/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-test.js
index 80e96bd1efd63..d69c626b4c0c0 100644
--- a/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-test.js
@@ -153,7 +153,7 @@ describe.each([
     }
 
     function useRefetchableFragmentNode(fragmentNode: any, fragmentRef: any) {
-      const result = useRefetchableFragmentNodeOriginal(
+      const result = useRefetchableFragmentNodeOriginal<any, any>(
         fragmentNode,
         fragmentRef,
         'TestDisplayName',
@@ -3074,7 +3074,7 @@ describe.each([
       describe('disposing', () => {
         const unsubscribe = jest.fn();
         jest.doMock('relay-runtime', () => {
-          const originalRuntime = jest.requireActual('relay-runtime');
+          const originalRuntime = jest.requireActual<any>('relay-runtime');
           const originalInternal = originalRuntime.__internal;
           return {
             ...originalRuntime,
diff --git a/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-with-suspense-transition-test.js b/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-with-suspense-transition-test.js
index 9dfa49ef56476..daef55abc9a1f 100644
--- a/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-with-suspense-transition-test.js
+++ b/packages/react-relay/relay-hooks/__tests__/useRefetchableFragmentNode-with-suspense-transition-test.js
@@ -56,7 +56,7 @@ describe('useRefetchableFragmentNode with useTransition', () => {
     ) {
       const [isPending, startTransition] = useTransition();
       const {fragmentData: data, ...result} =
-        useRefetchableFragmentNodeOriginal(
+        useRefetchableFragmentNodeOriginal<any, any>(
           fragmentNode,
           fragmentRef,
           'TestComponent',
diff --git a/packages/react-relay/relay-hooks/loadQuery.js b/packages/react-relay/relay-hooks/loadQuery.js
index 6372bba4f2a9e..647ed84f03076 100644
--- a/packages/react-relay/relay-hooks/loadQuery.js
+++ b/packages/react-relay/relay-hooks/loadQuery.js
@@ -120,7 +120,7 @@ function loadQuery<
   // of the operation, and then replay them to the Observable we
   // ultimately return.
   const executionSubject = new ReplaySubject();
-  const returnedObservable = Observable.create(sink =>
+  const returnedObservable = Observable.create<GraphQLResponse>(sink =>
     executionSubject.subscribe(sink),
   );
 
diff --git a/packages/react-relay/relay-hooks/preloadQuery_DEPRECATED.js b/packages/react-relay/relay-hooks/preloadQuery_DEPRECATED.js
index 83559bacdf959..66bcbad9b79d8 100644
--- a/packages/react-relay/relay-hooks/preloadQuery_DEPRECATED.js
+++ b/packages/react-relay/relay-hooks/preloadQuery_DEPRECATED.js
@@ -44,7 +44,7 @@ const WEAKMAP_SUPPORTED = typeof WeakMap === 'function';
 const STORE_OR_NETWORK_DEFAULT: PreloadFetchPolicy = 'store-or-network';
 
 const pendingQueriesByEnvironment = WEAKMAP_SUPPORTED
-  ? new WeakMap()
+  ? new WeakMap<IEnvironment, Map<string, PendingQueryEntry>>()
   : new Map();
 
 type PendingQueryEntry =
@@ -91,7 +91,7 @@ function preloadQuery<TQuery: OperationType, TEnvironmentProviderOptions>(
   );
   const source =
     queryEntry.kind === 'network'
-      ? Observable.create(sink => {
+      ? Observable.create<GraphQLResponse>(sink => {
           let subscription;
           if (pendingQueries.get(queryEntry.cacheKey) == null) {
             const newQueryEntry = preloadQueryDeduped(
diff --git a/packages/react-relay/relay-hooks/react-cache/__tests__/useLazyLoadQuery_REACT_CACHE-test.js b/packages/react-relay/relay-hooks/react-cache/__tests__/useLazyLoadQuery_REACT_CACHE-test.js
index 0fe781ec8a9e8..29f2e7e7de91b 100644
--- a/packages/react-relay/relay-hooks/react-cache/__tests__/useLazyLoadQuery_REACT_CACHE-test.js
+++ b/packages/react-relay/relay-hooks/react-cache/__tests__/useLazyLoadQuery_REACT_CACHE-test.js
@@ -659,7 +659,7 @@ describe('useLazyLoadQuery_REACT_CACHE', () => {
                 responseIsRejected &&
                 (shouldAwaitFetchResult || responseIsSynchronous);
 
-              const thrownPromises = new Set();
+              const thrownPromises = new Set<any>();
               let numberOfRendersObserved = 0;
               function TestComponent({output}: {output: boolean}) {
                 numberOfRendersObserved++;
diff --git a/packages/react-relay/relay-hooks/useLazyLoadQueryNode.js b/packages/react-relay/relay-hooks/useLazyLoadQueryNode.js
index c420fb0e5ee49..71f15bdb178b2 100644
--- a/packages/react-relay/relay-hooks/useLazyLoadQueryNode.js
+++ b/packages/react-relay/relay-hooks/useLazyLoadQueryNode.js
@@ -125,7 +125,7 @@ function useLazyLoadQueryNode<TQuery: OperationType>({
   });
 
   const {fragmentNode, fragmentRef} = preparedQueryResult;
-  const {data} = useFragmentNode(
+  const {data} = useFragmentNode<$FlowFixMe>(
     fragmentNode,
     fragmentRef,
     componentDisplayName,
diff --git a/packages/relay-runtime/handlers/connection/ConnectionHandler.js b/packages/relay-runtime/handlers/connection/ConnectionHandler.js
index 76f6ddaba149c..64ad418f80e1d 100644
--- a/packages/relay-runtime/handlers/connection/ConnectionHandler.js
+++ b/packages/relay-runtime/handlers/connection/ConnectionHandler.js
@@ -149,7 +149,7 @@ function update(store: RecordSourceProxy, payload: HandleFieldPayload): void {
           clientPageInfo &&
           args.after === clientPageInfo.getValue(END_CURSOR)
         ) {
-          const nodeIDs = new Set();
+          const nodeIDs = new Set<mixed>();
           mergeEdges(prevEdges, nextEdges, nodeIDs);
           mergeEdges(serverEdges, nextEdges, nodeIDs);
         } else {
@@ -168,7 +168,7 @@ function update(store: RecordSourceProxy, payload: HandleFieldPayload): void {
           clientPageInfo &&
           args.before === clientPageInfo.getValue(START_CURSOR)
         ) {
-          const nodeIDs = new Set();
+          const nodeIDs = new Set<mixed>();
           mergeEdges(serverEdges, nextEdges, nodeIDs);
           mergeEdges(prevEdges, nextEdges, nodeIDs);
         } else {
diff --git a/packages/relay-runtime/mutations/__tests__/readUpdatableQuery_EXPERIMENTAL-test.js b/packages/relay-runtime/mutations/__tests__/readUpdatableQuery_EXPERIMENTAL-test.js
index 224ea2322a017..d47f4019b34c8 100644
--- a/packages/relay-runtime/mutations/__tests__/readUpdatableQuery_EXPERIMENTAL-test.js
+++ b/packages/relay-runtime/mutations/__tests__/readUpdatableQuery_EXPERIMENTAL-test.js
@@ -290,7 +290,7 @@ describe('readUpdatableQuery', () => {
       ).updatableData;
 
       if (updatableData.node != null) {
-        const propertyDescriptor = Object.getOwnPropertyDescriptor(
+        const propertyDescriptor = Object.getOwnPropertyDescriptor<$FlowFixMe>(
           updatableData.node,
           'name',
         );
@@ -309,7 +309,7 @@ describe('readUpdatableQuery', () => {
       // Because node2 is not a user, selections within an inline fragment on User do not result
       // in a setter being created
       if (updatableData.node2 != null) {
-        const propertyDescriptor2 = Object.getOwnPropertyDescriptor(
+        const propertyDescriptor2 = Object.getOwnPropertyDescriptor<$FlowFixMe>(
           updatableData.node2,
           'name',
         );
diff --git a/packages/relay-runtime/query/fetchQueryInternal.js b/packages/relay-runtime/query/fetchQueryInternal.js
index 1ac449242cc3e..d5332430833ae 100644
--- a/packages/relay-runtime/query/fetchQueryInternal.js
+++ b/packages/relay-runtime/query/fetchQueryInternal.js
@@ -36,7 +36,7 @@ type RequestCacheEntry = {
 const WEAKMAP_SUPPORTED = typeof WeakMap === 'function';
 
 const requestCachesByEnvironment = WEAKMAP_SUPPORTED
-  ? new WeakMap()
+  ? new WeakMap<IEnvironment, Map<RequestIdentifier, RequestCacheEntry>>()
   : new Map();
 
 /**
diff --git a/packages/relay-runtime/store/RelayExperimentalGraphResponseTransform.js b/packages/relay-runtime/store/RelayExperimentalGraphResponseTransform.js
index 9b209ca30d03d..71e7a58b3669a 100644
--- a/packages/relay-runtime/store/RelayExperimentalGraphResponseTransform.js
+++ b/packages/relay-runtime/store/RelayExperimentalGraphResponseTransform.js
@@ -178,7 +178,7 @@ export class GraphModeNormalizer {
     if (maybeSent != null) {
       return maybeSent;
     }
-    const sent = new Set();
+    const sent = new Set<string>();
     this._sentFields.set(cacheKey, sent);
     return sent;
   }
diff --git a/packages/relay-runtime/store/RelayModernStore.js b/packages/relay-runtime/store/RelayModernStore.js
index 09a6578b40c32..de67c2934eb16 100644
--- a/packages/relay-runtime/store/RelayModernStore.js
+++ b/packages/relay-runtime/store/RelayModernStore.js
@@ -457,7 +457,7 @@ class RelayModernStore implements Store {
   }
 
   lookupInvalidationState(dataIDs: $ReadOnlyArray<DataID>): InvalidationState {
-    const invalidations = new Map();
+    const invalidations = new Map<DataID, ?number>();
     dataIDs.forEach(dataID => {
       const record = this.getSource().get(dataID);
       invalidations.set(
@@ -602,7 +602,7 @@ class RelayModernStore implements Store {
     /* eslint-disable no-labels */
     top: while (true) {
       const startEpoch = this._currentWriteEpoch;
-      const references = new Set();
+      const references = new Set<DataID>();
 
       // Mark all records that are traversable from a root
       for (const {operation} of this._roots.values()) {
diff --git a/packages/relay-runtime/store/RelayOperationTracker.js b/packages/relay-runtime/store/RelayOperationTracker.js
index feb8922b36399..986cce5d1c3e2 100644
--- a/packages/relay-runtime/store/RelayOperationTracker.js
+++ b/packages/relay-runtime/store/RelayOperationTracker.js
@@ -10,6 +10,7 @@
  */
 
 'use strict';
+import type {RequestIdentifier} from '../util/getRequestIdentifier';
 
 import type {RequestDescriptor} from './RelayStoreTypes';
 
@@ -45,7 +46,7 @@ class RelayOperationTracker {
       return;
     }
     const pendingOperationIdentifier = pendingOperation.identifier;
-    const newlyAffectedOwnersIdentifier = new Set();
+    const newlyAffectedOwnersIdentifier = new Set<RequestIdentifier>();
     for (const owner of affectedOwners) {
       const ownerIdentifier = owner.identifier;
       const pendingOperationsAffectingOwner =
@@ -105,11 +106,11 @@ class RelayOperationTracker {
       return;
     }
     // These were the owners affected only by `pendingOperationIdentifier`
-    const completedOwnersIdentifier = new Set();
+    const completedOwnersIdentifier = new Set<string>();
 
     // These were the owners affected by `pendingOperationIdentifier`
     // and some other operations
-    const updatedOwnersIdentifier = new Set();
+    const updatedOwnersIdentifier = new Set<string>();
     for (const ownerIdentifier of affectedOwnersIdentifier) {
       const pendingOperationsAffectingOwner =
         this._ownersToPendingOperations.get(ownerIdentifier);
diff --git a/packages/relay-runtime/store/__tests__/ClientID-test.js b/packages/relay-runtime/store/__tests__/ClientID-test.js
index 8e9cf613487c3..ff0f208263d9f 100644
--- a/packages/relay-runtime/store/__tests__/ClientID-test.js
+++ b/packages/relay-runtime/store/__tests__/ClientID-test.js
@@ -10,6 +10,7 @@
  */
 
 'use strict';
+import type {DataID} from 'relay-runtime/util/RelayRuntimeTypes';
 
 const {
   generateClientID,
@@ -18,7 +19,7 @@ const {
 } = require('../ClientID');
 
 it('creates unique local ids', () => {
-  const set = new Set();
+  const set = new Set<DataID>();
   for (let i = 0; i < 10; i++) {
     const id = generateUniqueClientID();
     expect(set.has(id)).toBe(false);
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ApplyUpdate-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ApplyUpdate-test.js
index 6405a16ca78d3..57cd5efc4caac 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ApplyUpdate-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ApplyUpdate-test.js
@@ -235,7 +235,7 @@ describe.each(['RelayModernEnvironment', 'MultiActorEnvironment'])(
 
         beforeEach(() => {
           taskID = 0;
-          tasks = new Map();
+          tasks = new Map<string, () => void>();
           scheduler = {
             cancel: (id: string) => {
               tasks.delete(id);
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitPayload-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitPayload-test.js
index a87f047f409e5..13d7d9f36d192 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitPayload-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitPayload-test.js
@@ -349,7 +349,7 @@ describe.each(['RelayModernEnvironment', 'MultiActorEnvironment'])(
 
         beforeEach(() => {
           taskID = 0;
-          tasks = new Map();
+          tasks = new Map<string, () => void>();
           scheduler = {
             cancel: (id: string) => {
               tasks.delete(id);
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitUpdate-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitUpdate-test.js
index c5f85c4af38ee..0c3453742d2ad 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitUpdate-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-CommitUpdate-test.js
@@ -103,7 +103,7 @@ describe.each(['RelayModernEnvironment', 'MultiActorEnvironment'])(
 
         beforeEach(() => {
           taskID = 0;
-          tasks = new Map();
+          tasks = new Map<string, () => void>();
           scheduler = {
             cancel: (id: string) => {
               tasks.delete(id);
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteMutationWithFlight-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteMutationWithFlight-test.js
index 4dce613b79667..be52b22db47b8 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteMutationWithFlight-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteMutationWithFlight-test.js
@@ -139,7 +139,7 @@ describe.each(['RelayModernEnvironment', 'MultiActorEnvironment'])(
           _variables: Variables,
           _cacheConfig: CacheConfig,
         ) => {
-          return RelayObservable.create(sink => {
+          return RelayObservable.create<any>(sink => {
             subject = sink;
           });
         };
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteSubscriptionWithMatch-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteSubscriptionWithMatch-test.js
index 0d76f6a788bb2..d99ef8b74d3db 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteSubscriptionWithMatch-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteSubscriptionWithMatch-test.js
@@ -705,7 +705,7 @@ describe.each(['RelayModernEnvironment', 'MultiActorEnvironment'])(
 
         beforeEach(() => {
           taskID = 0;
-          tasks = new Map();
+          tasks = new Map<string, () => void>();
           scheduler = {
             cancel: (id: string) => {
               tasks.delete(id);
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithFlight-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithFlight-test.js
index ac77d297eb367..6ca0917db99d7 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithFlight-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithFlight-test.js
@@ -98,7 +98,7 @@ describe.each(['RelayModernEnvironment', 'MultiActorEnvironment'])(
           _variables: Variables,
           _cacheConfig: CacheConfig,
         ) => {
-          return RelayObservable.create(sink => {
+          return RelayObservable.create<$FlowFixMe>(sink => {
             dataSource = sink;
           });
         };
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStream-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStream-test.js
index 2e1dd480502d0..ec8495993873f 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStream-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStream-test.js
@@ -117,7 +117,7 @@ describe('execute() a query with @stream', () => {
       _variables: Variables,
       _cacheConfig: CacheConfig,
     ) => {
-      return RelayObservable.create(sink => {
+      return RelayObservable.create<$FlowFixMe>(sink => {
         dataSource = sink;
       });
     };
@@ -503,7 +503,7 @@ describe('execute() a query with @stream', () => {
 
   it('processes streamed payloads with scheduling', () => {
     let taskID = 0;
-    const tasks = new Map();
+    const tasks = new Map<string, () => void>();
     const scheduler = {
       cancel: (id: string) => {
         tasks.delete(id);
@@ -604,7 +604,7 @@ describe('execute() a query with @stream', () => {
 
   it('cancels processing of streamed payloads with scheduling', () => {
     let taskID = 0;
-    const tasks = new Map();
+    const tasks = new Map<string, () => void>();
     const scheduler = {
       cancel: (id: string) => {
         tasks.delete(id);
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStreamedConnection-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStreamedConnection-test.js
index d219cf393db60..95b76caf4d449 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStreamedConnection-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-ExecuteWithStreamedConnection-test.js
@@ -125,7 +125,7 @@ describe('execute() fetches a @stream-ed @connection', () => {
       _variables: Variables,
       _cacheConfig: CacheConfig,
     ) => {
-      return RelayObservable.create(sink => {
+      return RelayObservable.create<$FlowFixMe>(sink => {
         dataSource = sink;
       });
     };
diff --git a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-isServer-test.js b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-isServer-test.js
index 2f62a69592360..31a0935bca51f 100644
--- a/packages/relay-runtime/store/__tests__/RelayModernEnvironment-isServer-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayModernEnvironment-isServer-test.js
@@ -23,7 +23,7 @@ const {disallowWarnings} = require('relay-test-utils-internal');
 disallowWarnings();
 
 describe('isServer', () => {
-  const fetch = () => Observable.create(() => {});
+  const fetch = () => Observable.create<any>(() => {});
   it('defaults to false', () => {
     const environment = new Environment({
       network: Network.create(fetch),
diff --git a/packages/relay-runtime/store/__tests__/RelayReferenceMarker-test.js b/packages/relay-runtime/store/__tests__/RelayReferenceMarker-test.js
index 55e80647a4ab2..2d19a2c026078 100644
--- a/packages/relay-runtime/store/__tests__/RelayReferenceMarker-test.js
+++ b/packages/relay-runtime/store/__tests__/RelayReferenceMarker-test.js
@@ -10,6 +10,7 @@
  */
 
 'use strict';
+import type {DataID} from 'relay-runtime/util/RelayRuntimeTypes';
 
 import RelayNetwork from '../../network/RelayNetwork';
 import RelayModernEnvironment from '../RelayModernEnvironment';
@@ -126,7 +127,7 @@ describe('RelayReferenceMarker', () => {
         }
       }
     `;
-    const references = new Set();
+    const references = new Set<DataID>();
     mark(
       source,
       createNormalizationSelector(FooQuery.operation, ROOT_ID, {
@@ -215,7 +216,7 @@ describe('RelayReferenceMarker', () => {
         }
       }
     `;
-    const references = new Set();
+    const references = new Set<DataID>();
     mark(
       source,
       createNormalizationSelector(UserProfile.operation, ROOT_ID, {
@@ -320,7 +321,7 @@ describe('RelayReferenceMarker', () => {
         }
       }
     `;
-    let references = new Set();
+    let references = new Set<DataID>();
     mark(
       source,
       createNormalizationSelector(UserProfile.operation, ROOT_ID, {
@@ -443,7 +444,7 @@ describe('RelayReferenceMarker', () => {
         }
       }
     `;
-    const references = new Set();
+    const references = new Set<DataID>();
     mark(
       source,
       createNormalizationSelector(FooQuery.operation, ROOT_ID, {
@@ -552,7 +553,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -605,7 +606,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -650,7 +651,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -706,7 +707,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -750,7 +751,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -791,7 +792,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -823,7 +824,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -849,7 +850,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -882,7 +883,7 @@ describe('RelayReferenceMarker', () => {
       };
 
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       const loader = {
         get: jest.fn(
           moduleName => nodes[String(moduleName).replace(/\$.*/, '')],
@@ -931,7 +932,7 @@ describe('RelayReferenceMarker', () => {
       };
 
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       const loader = {
         get: jest.fn(
           moduleName => nodes[String(moduleName).replace(/\$.*/, '')],
@@ -979,7 +980,7 @@ describe('RelayReferenceMarker', () => {
       };
 
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       const loader = {
         get: jest.fn(
           moduleName => nodes[String(moduleName).replace(/\$.*/, '')],
@@ -1103,7 +1104,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -1153,7 +1154,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -1195,7 +1196,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -1248,7 +1249,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -1289,7 +1290,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -1327,7 +1328,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         source,
         createNormalizationSelector(BarQuery.operation, 'client:root', {
@@ -1375,7 +1376,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       source = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       expect(() =>
         mark(
           source,
@@ -1435,7 +1436,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(Query.operation, 'client:root', {id: '1'}),
@@ -1459,7 +1460,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(Query.operation, 'client:root', {id: '1'}),
@@ -1511,7 +1512,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(Query.operation, 'client:root', {id: '1'}),
@@ -1535,7 +1536,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(storeData);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(Query.operation, 'client:root', {id: '1'}),
@@ -1638,7 +1639,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(data);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(FlightQuery.operation, 'client:root', {
@@ -1682,7 +1683,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(data);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(FlightQuery.operation, 'client:root', {
@@ -1722,7 +1723,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(data);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(FlightQuery.operation, 'client:root', {
@@ -1762,7 +1763,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(data);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(FlightQuery.operation, 'client:root', {
@@ -1800,7 +1801,7 @@ describe('RelayReferenceMarker', () => {
         },
       };
       const recordSource = RelayRecordSource.create(data);
-      const references = new Set();
+      const references = new Set<DataID>();
       mark(
         recordSource,
         createNormalizationSelector(FlightQuery.operation, 'client:root', {
diff --git a/packages/relay-runtime/store/experimental-live-resolvers/LiveResolverStore.js b/packages/relay-runtime/store/experimental-live-resolvers/LiveResolverStore.js
index f58e87d00c0d5..22facf9f1df15 100644
--- a/packages/relay-runtime/store/experimental-live-resolvers/LiveResolverStore.js
+++ b/packages/relay-runtime/store/experimental-live-resolvers/LiveResolverStore.js
@@ -501,7 +501,7 @@ class LiveResolverStore implements Store {
   // real RelayModernStore can create. For now we just use any.
   // $FlowFixMe
   lookupInvalidationState(dataIDs: $ReadOnlyArray<DataID>): any {
-    const invalidations = new Map();
+    const invalidations = new Map<DataID, ?number>();
     dataIDs.forEach(dataID => {
       const record = this.getSource().get(dataID);
       invalidations.set(
@@ -663,7 +663,7 @@ class LiveResolverStore implements Store {
     /* eslint-disable no-labels */
     top: while (true) {
       const startEpoch = this._currentWriteEpoch;
-      const references = new Set();
+      const references = new Set<DataID>();
 
       // Mark all records that are traversable from a root
       for (const {operation} of this._roots.values()) {
diff --git a/packages/relay-runtime/util/StringInterner.js b/packages/relay-runtime/util/StringInterner.js
index bb40310cd78db..b72650364b6d2 100644
--- a/packages/relay-runtime/util/StringInterner.js
+++ b/packages/relay-runtime/util/StringInterner.js
@@ -11,7 +11,7 @@
 
 'use strict';
 
-const internTable = new Map();
+const internTable = new Map<string, string>();
 let nextIndex = 1;
 const digits = initDigitTable();
 
@@ -26,7 +26,7 @@ const ESCAPE_PREFIX = '\v';
 function initDigitTable() {
   // disable lint because digits isn't defined when this function is called
   // eslint-disable-next-line no-shadow
-  const digits = new Set();
+  const digits = new Set<string>();
   for (let i = 0; i < 10; ++i) {
     digits.add(i.toString());
   }
diff --git a/packages/relay-test-utils-internal/trackRetentionForEnvironment.js b/packages/relay-test-utils-internal/trackRetentionForEnvironment.js
index cd42005358fb2..6131233edc55d 100644
--- a/packages/relay-test-utils-internal/trackRetentionForEnvironment.js
+++ b/packages/relay-test-utils-internal/trackRetentionForEnvironment.js
@@ -26,7 +26,7 @@ function trackRetentionForEnvironment(environment: IEnvironment): {
   release_DEPRECATED: JestMockFn<[mixed], void>,
   isOperationRetained: OperationDescriptor => boolean,
 } {
-  const retainCountsByOperation = new Map();
+  const retainCountsByOperation = new Map<mixed, number>();
 
   const release = jest.fn(id => {
     const existing = retainCountsByOperation.get(id) ?? NaN;