diff --git a/src/compiler/node_generator.cc b/src/compiler/node_generator.cc
index 7605b64531e1514d10a66b1f1e085190ad37fff6..03e1314f7bae3bde70cd4a80e05b539c23119a44 100644
--- a/src/compiler/node_generator.cc
+++ b/src/compiler/node_generator.cc
@@ -97,10 +97,10 @@ grpc::string GetRelativePath(const grpc::string& from_file,
  * as a map of fully qualified message type name to message descriptor */
 map<grpc::string, const Descriptor*> GetAllMessages(const FileDescriptor *file) {
   map<grpc::string, const Descriptor*> message_types;
-  for (int i = 0; i < file->service_count(); i++) {
-    const ServiceDescriptor* service = file->service(i);
-    for (int j = 0; j < service->method_count(); j++) {
-      const MethodDescriptor* method = service->method(i);
+  for (int service_num = 0; service_num < file->service_count(); service_num++) {
+    const ServiceDescriptor* service = file->service(service_num);
+    for (int method_num = 0; method_num < service->method_count(); method_num++) {
+      const MethodDescriptor* method = service->method(method_num);
       const Descriptor* input_type = method->input_type();
       const Descriptor* output_type = method->output_type();
       message_types[input_type->name()] = input_type;