diff --git a/DataFormats/Common/interface/BaseHolder.h b/DataFormats/Common/interface/BaseHolder.h
index 67fc5f253acd9..ea22d3ac25452 100644
--- a/DataFormats/Common/interface/BaseHolder.h
+++ b/DataFormats/Common/interface/BaseHolder.h
@@ -9,9 +9,9 @@
 
 namespace edm {
   class ProductID;
-  class RefHolderBase;
 
   namespace reftobase {
+    class RefHolderBase;
     template<typename T> class BaseVectorHolder;
     class RefVectorHolderBase;