diff --git a/core/tw-timing.h b/core/tw-timing.h
index 5e648a0d..ec6a24ab 100644
--- a/core/tw-timing.h
+++ b/core/tw-timing.h
@@ -1,6 +1,8 @@
 #ifndef INC_tw_timing_h
 #define INC_tw_timing_h
 
+#include <sys/time.h>
+
 typedef struct timeval tw_wtime;
 
 #endif