diff --git a/watch-library/shared/watch/watch_utility.c b/watch-library/shared/watch/watch_utility.c
index 013078a8..308159d6 100644
--- a/watch-library/shared/watch/watch_utility.c
+++ b/watch-library/shared/watch/watch_utility.c
@@ -23,6 +23,7 @@
  */
 
 #include <math.h>
+#include <string.h>
 #include "watch_utility.h"
 #include "zones.h"