diff --git a/packages/proto-loader/bin/proto-loader-gen-types.ts b/packages/proto-loader/bin/proto-loader-gen-types.ts
index 4b11cc30..0f3b82e8 100644
--- a/packages/proto-loader/bin/proto-loader-gen-types.ts
+++ b/packages/proto-loader/bin/proto-loader-gen-types.ts
@@ -125,7 +125,7 @@ function generatePermissiveMessageInterface(formatter: TextFormatter, messageTyp
         type = 'string';
         break;
       case 'bytes':
-        type = 'Buffer | UInt8Array | String';
+        type = 'Buffer | Uint8Array | string';
         break;
       default:
         if (field.resolvedType === null) {
@@ -188,7 +188,7 @@ function generateRestrictedMessageInterface(formatter: TextFormatter, messageTyp
         if (options.bytes === Array) {
           type = 'Uint8Array';
         } else if (options.bytes === String) {
-          type = 'String';
+          type = 'string';
         } else {
           type = 'Buffer';
         }
diff --git a/packages/proto-loader/package.json b/packages/proto-loader/package.json
index 849e0146..2bf93d42 100644
--- a/packages/proto-loader/package.json
+++ b/packages/proto-loader/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@grpc/proto-loader",
-  "version": "0.6.0-pre1",
+  "version": "0.6.0-pre2",
   "author": "Google Inc.",
   "contributors": [
     {