diff --git a/sim_defs.h b/sim_defs.h
index 761a1108..8d495c69 100644
--- a/sim_defs.h
+++ b/sim_defs.h
@@ -108,6 +108,7 @@
 #ifndef SIM_DEFS_H_
 #define SIM_DEFS_H_    0
 
+#include "sim_rev.h"
 #include <stddef.h>
 #include <stdlib.h>
 #include <stdio.h>