diff --git a/packages/proto-loader/src/index.ts b/packages/proto-loader/src/index.ts
index 9182fa8a..cf5976bc 100644
--- a/packages/proto-loader/src/index.ts
+++ b/packages/proto-loader/src/index.ts
@@ -250,7 +250,18 @@ function createSerializer(cls: Protobuf.Type): Serialize<object> {
 }
 
 function mapMethodOptions(options: Partial<MethodOptions>[] | undefined): MethodOptions {
-  return (options || []).reduce((obj: MethodOptions, item: Partial<MethodOptions>) => ({ ...obj, ...item  }),
+  return (options || []).reduce((obj: MethodOptions, item: Partial<MethodOptions>) => {
+    for (const [key, value] of Object.entries(item)) {
+      switch (key) {
+        case 'uninterpreted_option' :
+          obj.uninterpreted_option.push(item.uninterpreted_option as UninterpretedOption);
+          break;
+        default:
+          obj[key] = value
+      }
+    }
+    return obj
+  },
     {
       deprecated: false,
       idempotency_level: IdempotencyLevel.IDEMPOTENCY_UNKNOWN,
diff --git a/packages/proto-loader/test/descriptor_type_test.ts b/packages/proto-loader/test/descriptor_type_test.ts
index f9994979..7a2ed393 100644
--- a/packages/proto-loader/test/descriptor_type_test.ts
+++ b/packages/proto-loader/test/descriptor_type_test.ts
@@ -140,10 +140,10 @@ describe('Descriptor types', () => {
     assert.deepStrictEqual(service.Hello.options, {
       deprecated: true,
       idempotency_level: 'NO_SIDE_EFFECTS',
-      uninterpreted_option: {
+      uninterpreted_option: [{
         name: {
           name_part: 'foo',
-          is_extension:  false,
+          is_extension: false,
         },
         identifier_value: 'bar',
         positive_int_value: 9007199254740991,
@@ -151,7 +151,7 @@ describe('Descriptor types', () => {
         double_value: 1.2345,
         string_value: 'foobar',
         aggregate_value: 'foobar'
-      },
+      }],
       '(google.api.http)': {
         post: '/hello',
         body: '*',