diff --git a/mozilla/lib/mac/MacMemoryAllocator/src/nsGCStubs.c b/mozilla/lib/mac/MacMemoryAllocator/src/nsGCStubs.c
index ddc370a7fe6..c303e381984 100644
--- a/mozilla/lib/mac/MacMemoryAllocator/src/nsGCStubs.c
+++ b/mozilla/lib/mac/MacMemoryAllocator/src/nsGCStubs.c
@@ -59,4 +59,7 @@ void MWUnmangle(const char *mangled_name, char *unmangled_name, size_t buffersiz
 	strncpy(unmangled_name, mangled_name, buffersize);
 }
 
+void GC_trace_object(void* object);
+void GC_trace_object(void* object) {}
+
 #endif