diff --git a/packages/react-native-codegen/src/parsers/flow/modules/index.js b/packages/react-native-codegen/src/parsers/flow/modules/index.js
index af2ce50a985c3c..fae2c38d0a3b4b 100644
--- a/packages/react-native-codegen/src/parsers/flow/modules/index.js
+++ b/packages/react-native-codegen/src/parsers/flow/modules/index.js
@@ -173,6 +173,7 @@ function translateTypeAnnotation(
         );
         if (indexers.length > 0) {
           // check the property type to prevent developers from using unsupported types
+          // the return value from `translateTypeAnnotation` is unused
           const propertyType = indexers[0].value;
           translateTypeAnnotation(
             hasteModuleName,
@@ -259,8 +260,9 @@ function translateTypeAnnotation(
     case 'MixedTypeAnnotation': {
       if (cxxOnly) {
         return emitMixed(nullable);
+      } else {
+        return emitObject(nullable);
       }
-      // Fallthrough
     }
     default: {
       throw new UnsupportedTypeAnnotationParserError(
diff --git a/packages/react-native-codegen/src/parsers/typescript/modules/index.js b/packages/react-native-codegen/src/parsers/typescript/modules/index.js
index cbf1781c08d961..7c1750ad3354e5 100644
--- a/packages/react-native-codegen/src/parsers/typescript/modules/index.js
+++ b/packages/react-native-codegen/src/parsers/typescript/modules/index.js
@@ -191,6 +191,7 @@ function translateTypeAnnotation(
         );
         if (indexSignatures.length > 0) {
           // check the property type to prevent developers from using unsupported types
+          // the return value from `translateTypeAnnotation` is unused
           const propertyType = indexSignatures[0].typeAnnotation;
           translateTypeAnnotation(
             hasteModuleName,