diff --git a/lib/CodeGen/InstrSched/SchedGraph.h b/lib/CodeGen/InstrSched/SchedGraph.h
index e12d90ffcdd..35cdfd2513b 100644
--- a/lib/CodeGen/InstrSched/SchedGraph.h
+++ b/lib/CodeGen/InstrSched/SchedGraph.h
@@ -33,6 +33,7 @@ class SchedGraphEdge;
 class SchedGraphNode; 
 class SchedGraph; 
 class NodeToRegRefMap;
+class MachineInstr;
 
 /******************** Exported Data Types and Constants ********************/