diff --git a/core/definitions.mk b/core/definitions.mk
index 1afc0f4..f385b74 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -843,11 +843,13 @@
 @echo "Protoc: $@ <= $(PRIVATE_PROTO_SRC_FILES)"
 @rm -rf $(PRIVATE_PROTO_JAVA_OUTPUT_DIR)
 @mkdir -p $(PRIVATE_PROTO_JAVA_OUTPUT_DIR)
-$(hide) $(PROTOC) \
-	$(addprefix --proto_path=, $(PRIVATE_PROTO_INCLUDES)) \
-	$(PRIVATE_PROTO_JAVA_OUTPUT_OPTION)=$(PRIVATE_PROTO_JAVA_OUTPUT_DIR) \
-	$(PRIVATE_PROTOC_FLAGS) \
-	$(PRIVATE_PROTO_SRC_FILES)
+$(hide) for f in $(PRIVATE_PROTO_SRC_FILES); do \
+        $(PROTOC) \
+        $(addprefix --proto_path=, $(PRIVATE_PROTO_INCLUDES)) \
+        $(PRIVATE_PROTO_JAVA_OUTPUT_OPTION)=$(PRIVATE_PROTO_JAVA_OUTPUT_DIR) \
+        $(PRIVATE_PROTOC_FLAGS) \
+        $$f; \
+        done
 $(hide) touch $@
 endef