diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 7dcf342..d41f923 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -205,19 +205,22 @@ do { \
 	matches = completion_matches(text, complete_from_versioned_schema_query); \
 } while (0)
 
+/*
+ * Caution: COMPLETE_WITH_CONST is not for general-purpose use; you probably
+ * want COMPLETE_WITH() with one element, instead.
+ */
+#define COMPLETE_WITH_CONST(cs, con) \
+do { \
+	completion_case_sensitive = (cs); \
+	completion_charp = (con); \
+	matches = completion_matches(text, complete_from_const); \
+} while (0)
+
 #define COMPLETE_WITH_LIST_INT(cs, list) \
 do { \
 	completion_case_sensitive = (cs); \
-	if (!(list)[1]) \
-	{ \
-		completion_charp = (list)[0]; \
-		matches = completion_matches(text, complete_from_const); \
-	} \
-	else \
-	{ \
-		completion_charpp = (list); \
-		matches = completion_matches(text, complete_from_list); \
-	} \
+	completion_charpp = (list); \
+	matches = completion_matches(text, complete_from_list); \
 } while (0)
 
 #define COMPLETE_WITH_LIST(list) COMPLETE_WITH_LIST_INT(false, list)
@@ -3745,7 +3748,7 @@ psql_completion(const char *text, int start, int end)
 	 */
 	if (matches == NULL)
 	{
-		COMPLETE_WITH("");
+		COMPLETE_WITH_CONST(true, "");
 #ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
 		rl_completion_append_character = '\0';
 #endif
@@ -4177,8 +4180,10 @@ complete_from_list(const char *text, int state)
  * This function returns one fixed string the first time even if it doesn't
  * match what's there, and nothing the second time. This should be used if
  * there is only one possibility that can appear at a certain spot, so
- * misspellings will be overwritten.  The string to be passed must be in
- * completion_charp.
+ * misspellings will be overwritten.  (Caution: in practice that's almost
+ * never a good idea.  We currently use this function only for forcing
+ * readline to not attempt filename completion by default.)  The string
+ * to be passed must be in completion_charp.
  */
 static char *
 complete_from_const(const char *text, int state)