diff --git a/revision.h b/revision.h
index e7f1d211b..89132df2f 100644
--- a/revision.h
+++ b/revision.h
@@ -5,6 +5,7 @@
 #include "grep.h"
 #include "notes.h"
 #include "commit.h"
+#include "diff.h"
 
 #define SEEN		(1u<<0)
 #define UNINTERESTING   (1u<<1)