diff --git a/watchman/thirdparty/wildmatch/wildmatch.c b/watchman/thirdparty/wildmatch/wildmatch.c
index 3e24c384e1a2..5cd7b1d764ad 100644
--- a/watchman/thirdparty/wildmatch/wildmatch.c
+++ b/watchman/thirdparty/wildmatch/wildmatch.c
@@ -87,7 +87,7 @@ static int dowild(const uchar *p, const uchar *text, unsigned int flags)
 				/* Literal match with following character.  Note that the test
 				 * in "default" handles the p[1] == '\0' failure case. */
 				p_ch = *++p;
-			/* FALLTHROUGH */
+			__attribute__((fallthrough));
 		default:
 			if (p_ch == '/') {
 				/* Consume any number of consecutive slashes. */