diff --git a/migration-engine/core/src/state.rs b/migration-engine/core/src/state.rs
index 2b9a6db01d02..f341309132dc 100644
--- a/migration-engine/core/src/state.rs
+++ b/migration-engine/core/src/state.rs
@@ -322,7 +322,7 @@ impl GenericApi for EngineState {
             &params.schema,
             None,
             Box::new(move |connector| {
-                let composite_type_depth = From::from(params.composite_type_depth as isize);
+                let composite_type_depth = From::from(params.composite_type_depth);
                 let ctx = migration_connector::IntrospectionContext::new(schema, composite_type_depth);
                 Box::pin(async move {
                     // TODO(MultiSchema): Grab namespaces from introspect params?
diff --git a/migration-engine/json-rpc-api-build/methods/introspect.toml b/migration-engine/json-rpc-api-build/methods/introspect.toml
index 1cde040e65db..6e6f46541328 100644
--- a/migration-engine/json-rpc-api-build/methods/introspect.toml
+++ b/migration-engine/json-rpc-api-build/methods/introspect.toml
@@ -13,7 +13,7 @@ shape = "string"
 shape = "bool"
 
 [recordShapes.introspectParams.fields.compositeTypeDepth]
-shape = "u32"
+shape = "isize"
 
 [recordShapes.introspectResult]
 description = "Result type for the introspect method."
diff --git a/migration-engine/json-rpc-api-build/src/lib.rs b/migration-engine/json-rpc-api-build/src/lib.rs
index f7b0dd8970d5..0c73438580a1 100644
--- a/migration-engine/json-rpc-api-build/src/lib.rs
+++ b/migration-engine/json-rpc-api-build/src/lib.rs
@@ -85,7 +85,7 @@ fn validate(api: &Api) {
 }
 
 fn shape_exists(shape: &str, api: &Api) -> bool {
-    let builtin_scalars = ["string", "bool", "u32"];
+    let builtin_scalars = ["string", "bool", "u32", "isize"];
 
     if builtin_scalars.contains(&shape) {
         return true;
diff --git a/migration-engine/json-rpc-api-build/src/rust_crate.rs b/migration-engine/json-rpc-api-build/src/rust_crate.rs
index 63814fff40bf..fa57128f80d8 100644
--- a/migration-engine/json-rpc-api-build/src/rust_crate.rs
+++ b/migration-engine/json-rpc-api-build/src/rust_crate.rs
@@ -156,6 +156,7 @@ fn rustify_type_name(name: &str) -> Cow<'static, str> {
     match name {
         "bool" => Cow::Borrowed("bool"),
         "u32" => Cow::Borrowed("u32"),
+        "isize" => Cow::Borrowed("isize"),
         "string" => Cow::Borrowed("String"),
         other => other.to_camel_case().into(),
     }