diff --git a/src/backend/utils/adt/acl.c b/src/backend/utils/adt/acl.c
index 01caa12eca7..84803351f18 100644
--- a/src/backend/utils/adt/acl.c
+++ b/src/backend/utils/adt/acl.c
@@ -235,6 +235,10 @@ putid(char *p, const char *s)
 			break;
 		}
 	}
+	/* If name is all-digits, quote it to distinguish from lookup failure */
+	if (safe && strspn(s, "0123456789") == strlen(s))
+		safe = false;
+
 	if (!safe)
 		*p++ = '"';
 	for (src = s; *src; src++)