diff --git a/lib/rb/ext/strlcpy.h b/lib/rb/ext/strlcpy.h
index b37f6f4..c6f508f 100644
--- a/lib/rb/ext/strlcpy.h
+++ b/lib/rb/ext/strlcpy.h
@@ -18,11 +18,12 @@
  */
 
 
+#include <sys/types.h>
 #include <string.h>
 
 #ifndef HAVE_STRLCPY
 size_t
-strlcpy (char *dst, const char *src, size_t dst_sz)
+strlcpy (char *dst, const char *src, size_t dst_sz);
 #else
 extern size_t strlcpy(char *, const char *, size_t);
 #endif