diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c
index 26e0634833..6a8c360209 100644
--- a/src/backend/utils/adt/like_support.c
+++ b/src/backend/utils/adt/like_support.c
@@ -1449,7 +1449,14 @@ pattern_char_isalpha(char c, bool is_multibyte,
 	else if (is_multibyte && IS_HIGHBIT_SET(c))
 		return true;
 	else if (locale && locale->provider == COLLPROVIDER_ICU)
-		return IS_HIGHBIT_SET(c) ? true : false;
+	{
+#ifdef USE_ICU
+		return u_isalpha(c);
+#else
+		/* shouldn't happen */
+		elog(ERROR, "unsupported collprovider: %c", locale->provider);
+#endif
+	}
 #ifdef HAVE_LOCALE_T
 	else if (locale && locale->provider == COLLPROVIDER_LIBC)
 		return isalpha_l((unsigned char) c, locale->info.lt);