diff --git a/modules/i3-common.c b/modules/i3-common.c
index 0da04a5..225678b 100644
--- a/modules/i3-common.c
+++ b/modules/i3-common.c
@@ -1,6 +1,7 @@
 #include "i3-common.h"
 
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <assert.h>