diff --git a/src/include/port/pg_utf8.h b/src/include/port/pg_utf8.h
index a0c94dd4f3..62272a7c93 100644
--- a/src/include/port/pg_utf8.h
+++ b/src/include/port/pg_utf8.h
@@ -53,6 +53,7 @@ extern int pg_validate_utf8_fallback(const unsigned char *s, int len);
 static inline int
 check_ascii(const unsigned char *s, int len)
 {
+#if SIZEOF_VOID_P >= 8
 	uint64		chunk,
 				highbit_mask;
 
@@ -75,7 +76,9 @@ check_ascii(const unsigned char *s, int len)
 		else
 			return 0;
 	}
-
+	else
+		return 0;
+#endif
 	return 0;
 }