diff --git a/.changeset/wise-nails-design.md b/.changeset/wise-nails-design.md
new file mode 100644
index 00000000000..cede0d18dc0
--- /dev/null
+++ b/.changeset/wise-nails-design.md
@@ -0,0 +1,5 @@
+---
+"@smithy/core": patch
+---
+
+fix detection of member idempotencyToken trait
diff --git a/packages/core/src/submodules/cbor/CborCodec.spec.ts b/packages/core/src/submodules/cbor/CborCodec.spec.ts
index 91bccbac78d..d16134af89d 100644
--- a/packages/core/src/submodules/cbor/CborCodec.spec.ts
+++ b/packages/core/src/submodules/cbor/CborCodec.spec.ts
@@ -30,16 +30,18 @@ describe(CborShapeSerializer.name, () => {
             "ns",
             "StructWithIdempotencyToken",
             0,
-            ["idempotencyToken", "plainString"],
-            [idempotencyTokenSchema, plainSchema]
+            ["idempotencyToken", "plainString", "memberTraitToken"],
+            [idempotencyTokenSchema, plainSchema, [() => plainSchema, 0b0100]]
           );
 
           serializer.write(objectSchema, {
             idempotencyToken: undefined,
             plainString: undefined,
+            memberTraitToken: undefined,
           });
           expect(cbor.deserialize(serializer.flush())).toMatchObject({
             idempotencyToken: UUID_V4,
+            memberTraitToken: UUID_V4,
           });
 
           serializer.write(objectSchema, {
@@ -49,6 +51,18 @@ describe(CborShapeSerializer.name, () => {
           expect(cbor.deserialize(serializer.flush())).toMatchObject({
             idempotencyToken: UUID_V4,
             plainString: /^abc$/,
+            memberTraitToken: UUID_V4,
+          });
+
+          serializer.write(objectSchema, {
+            idempotencyToken: "jrt",
+            plainString: "abc",
+            memberTraitToken: "qrf",
+          });
+          expect(cbor.deserialize(serializer.flush())).toMatchObject({
+            idempotencyToken: "jrt",
+            plainString: /^abc$/,
+            memberTraitToken: "qrf",
           });
         }
       }
diff --git a/packages/core/src/submodules/schema/schemas/NormalizedSchema.spec.ts b/packages/core/src/submodules/schema/schemas/NormalizedSchema.spec.ts
index 1c057a72b09..36a868faaac 100644
--- a/packages/core/src/submodules/schema/schemas/NormalizedSchema.spec.ts
+++ b/packages/core/src/submodules/schema/schemas/NormalizedSchema.spec.ts
@@ -257,6 +257,18 @@ describe(NormalizedSchema.name, () => {
         expect(schema.getMergedTraits().idempotencyToken).toBe(undefined);
       }
     });
+
+    it("can understand members with the idempotencyToken trait", () => {
+      for (const schema of plainSchemas) {
+        expect(schema.isIdempotencyToken()).toBe(false);
+        expect(schema.getMergedTraits().idempotencyToken).toBe(undefined);
+
+        const structure = struct("", "StructureWithIdempotencyTokenMember", 0, ["token"], [[() => schema, 0b0100]]);
+        const ns = NormalizedSchema.of(structure).getMemberSchema("token");
+
+        expect(ns.isIdempotencyToken()).toBe(true);
+      }
+    });
   });
 
   describe("event stream detection", () => {
diff --git a/packages/core/src/submodules/schema/schemas/NormalizedSchema.ts b/packages/core/src/submodules/schema/schemas/NormalizedSchema.ts
index af7e8f86a0b..55887721d47 100644
--- a/packages/core/src/submodules/schema/schemas/NormalizedSchema.ts
+++ b/packages/core/src/submodules/schema/schemas/NormalizedSchema.ts
@@ -64,8 +64,9 @@ export class NormalizedSchema implements INormalizedSchema {
     }
 
     if (schema instanceof NormalizedSchema) {
+      const computedMemberTraits = this.memberTraits;
       Object.assign(this, schema);
-      this.memberTraits = Object.assign({}, schema.getMemberTraits(), this.getMemberTraits());
+      this.memberTraits = Object.assign({}, computedMemberTraits, schema.getMemberTraits(), this.getMemberTraits());
       this.normalizedTraits = void 0;
       this.memberName = memberName ?? schema.memberName;
       return;
@@ -255,10 +256,19 @@ export class NormalizedSchema implements INormalizedSchema {
    * @returns whether the schema has the idempotencyToken trait.
    */
   public isIdempotencyToken(): boolean {
-    if (typeof this.traits === "number") {
-      return (this.traits & 0b0100) === 0b0100;
-    } else if (typeof this.traits === "object") {
-      return !!this.traits.idempotencyToken;
+    if (this.normalizedTraits) {
+      return !!this.normalizedTraits.idempotencyToken;
+    }
+    for (const traits of [this.traits, this.memberTraits]) {
+      if (typeof traits === "number") {
+        if ((traits & 0b0100) === 0b0100) {
+          return true;
+        }
+      } else if (typeof traits === "object") {
+        if (!!traits.idempotencyToken) {
+          return true;
+        }
+      }
     }
     return false;
   }
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/schema/SchemaGenerator.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/schema/SchemaGenerator.java
index c98e24dc2ec..861daa85b67 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/schema/SchemaGenerator.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/schema/SchemaGenerator.java
@@ -103,12 +103,16 @@ public void run() {
                 return;
             }
             for (OperationShape operation : TopDownIndex.of(model).getContainedOperations(service)) {
-                operation.getInput().ifPresent(inputShape -> {
-                    loadShapes(model.expectShape(inputShape));
-                });
-                operation.getOutput().ifPresent(outputShape -> {
-                    loadShapes(model.expectShape(outputShape));
-                });
+                if (operation.getInput().isPresent()) {
+                    loadShapes(model.expectShape(operation.getInput().get()));
+                } else {
+                    loadShapes(model.expectShape(ShapeId.from("smithy.api#Unit")));
+                }
+                if (operation.getOutput().isPresent()) {
+                    loadShapes(model.expectShape(operation.getOutput().get()));
+                } else {
+                    loadShapes(model.expectShape(ShapeId.from("smithy.api#Unit")));
+                }
                 operation.getErrors().forEach(error -> {
                     loadShapes(model.expectShape(error));
                 });