diff --git a/src/backend/parser/parse_param.c b/src/backend/parser/parse_param.c
index 53f3d625d039c845e99124982ab961a955646b30..b1282a14626679be7c6832b2faf2689452ca1006 100644
--- a/src/backend/parser/parse_param.c
+++ b/src/backend/parser/parse_param.c
@@ -17,7 +17,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_param.c,v 2.2 2010/01/02 16:57:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_param.c,v 2.3 2010/01/13 01:17:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -100,8 +100,9 @@ fixed_paramref_hook(ParseState *pstate, ParamRef *pref)
 	int			paramno = pref->number;
 	Param	   *param;
 
-	/* Check parameter number is in range */
-	if (paramno <= 0 || paramno > parstate->numParams)
+	/* Check parameter number is valid */
+	if (paramno <= 0 || paramno > parstate->numParams ||
+		!OidIsValid(parstate->paramTypes[paramno - 1]))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_PARAMETER),
 				 errmsg("there is no parameter $%d", paramno),