diff --git a/textcode/fmt_jsonescape.c b/textcode/fmt_jsonescape.c
index 4c78046..eb97b10 100644
--- a/textcode/fmt_jsonescape.c
+++ b/textcode/fmt_jsonescape.c
@@ -1,3 +1,4 @@
+#include <string.h>
 #include "fmt.h"
 #include "textcode.h"
 #include "str.h"