diff --git a/src/backend/utils/adt/like_match.c b/src/backend/utils/adt/like_match.c
index defcaa96fb5..0249eb49a7d 100644
--- a/src/backend/utils/adt/like_match.c
+++ b/src/backend/utils/adt/like_match.c
@@ -75,7 +75,8 @@
  * locales must casefold the inputs before matching.
  */
 #ifdef MATCH_LOWER
-#define GETCHAR(t) pg_ascii_tolower(t)
+/* cast to char to match data types in caller */
+#define GETCHAR(t) ((char) pg_ascii_tolower(t))
 #else
 #define GETCHAR(t) (t)
 #endif