diff --git a/dtool/src/interrogate/functionWriters.h b/dtool/src/interrogate/functionWriters.h
index 0db121de10..41943c47f7 100644
--- a/dtool/src/interrogate/functionWriters.h
+++ b/dtool/src/interrogate/functionWriters.h
@@ -42,7 +42,7 @@ protected:
     }
   };
 
-  typedef set<FunctionWriter *, IndirectCompareTo> Writers;
+  typedef std::set<FunctionWriter *, IndirectCompareTo> Writers;
   Writers _writers;
 };