diff --git a/README.md b/README.md
index a0018a5..3548164 100644
--- a/README.md
+++ b/README.md
@@ -230,9 +230,9 @@ This list is replicated (hopefully correctly) below.
 
 Versions specified by the inputs, e.g. `ghc-version`, are resolved against this list,
 by taking the first entry from the list if `latest` is requested,
-or the first entry that is a (string-)extension of the requested version otherwise.
-E.g., `8.10` will be resolved to `8.10.7`, and so will `8.10.`, `8.` and `8`
-(and incorrectly, [even `8.1`](github.com/haskell/actions/issues/248)).
+or the first entry that matches exactly,
+or otherwise the first entry that is a (string-)extension of the requested version extended by a `.`.
+E.g., `8.10` will be resolved to `8.10.7`, and so will `8`.
 
 **GHC:**
 
diff --git a/__tests__/find-haskell.test.ts b/__tests__/find-haskell.test.ts
index acd9193..5aaa396 100644
--- a/__tests__/find-haskell.test.ts
+++ b/__tests__/find-haskell.test.ts
@@ -96,13 +96,13 @@ describe('haskell/actions/setup', () => {
     });
   });
 
-  it('Versions resolve as string prefix (resolving 8.1 to 8.10.x should be considered a bug)', () => {
+  it('Versions resolve as version prefix', () => {
     const v = {ghc: '8.10.7', cabal: '2.4.1.0', stack: '2.1.3'};
     forAllOS(os => {
       const options = getOpts(def(os), os, {
         'enable-stack': 'true',
         'stack-version': '2.1',
-        'ghc-version': '8.1',
+        'ghc-version': '8.10',
         'cabal-version': '2'
       });
       forAllTools(t => expect(options[t].resolved).toBe(v[t]));
diff --git a/dist/index.js b/dist/index.js
index c9523e5..c9dc01b 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -13750,7 +13750,11 @@ function resolve(version, supported, tool, os, verbose // If resolution isn't th
 ) {
     const result = version === 'latest'
         ? supported[0]
-        : supported.find(v => v.startsWith(version)) ?? version;
+        : supported.find(v => v === version) ??
+            supported.find(v => v.startsWith(version + '.')) ??
+            // Andreas, 2023-05-19, issue #248
+            // Append "." so that eg stack "2.1" resolves to "2.1.3" and not "2.11.1".
+            version;
     // Andreas 2022-12-29, issue #144: inform about resolution here where we can also output ${tool}.
     if (verbose === true && version !== result)
         core.info(`Resolved ${tool} ${version} to ${result}`);
diff --git a/lib/opts.js b/lib/opts.js
index 599f4ec..fb933de 100644
--- a/lib/opts.js
+++ b/lib/opts.js
@@ -84,7 +84,11 @@ function resolve(version, supported, tool, os, verbose // If resolution isn't th
 ) {
     const result = version === 'latest'
         ? supported[0]
-        : supported.find(v => v.startsWith(version)) ?? version;
+        : supported.find(v => v === version) ??
+            supported.find(v => v.startsWith(version + '.')) ??
+            // Andreas, 2023-05-19, issue #248
+            // Append "." so that eg stack "2.1" resolves to "2.1.3" and not "2.11.1".
+            version;
     // Andreas 2022-12-29, issue #144: inform about resolution here where we can also output ${tool}.
     if (verbose === true && version !== result)
         core.info(`Resolved ${tool} ${version} to ${result}`);
diff --git a/src/opts.ts b/src/opts.ts
index 4fff340..9fe2dc1 100644
--- a/src/opts.ts
+++ b/src/opts.ts
@@ -97,7 +97,11 @@ function resolve(
   const result =
     version === 'latest'
       ? supported[0]
-      : supported.find(v => v.startsWith(version)) ?? version;
+      : supported.find(v => v === version) ??
+        supported.find(v => v.startsWith(version + '.')) ??
+        // Andreas, 2023-05-19, issue #248
+        // Append "." so that eg stack "2.1" resolves to "2.1.3" and not "2.11.1".
+        version;
   // Andreas 2022-12-29, issue #144: inform about resolution here where we can also output ${tool}.
   if (verbose === true && version !== result)
     core.info(`Resolved ${tool} ${version} to ${result}`);