diff --git a/src/pl/plpgsql/src/pl_comp.c b/src/pl/plpgsql/src/pl_comp.c
index 38b3d077de21221011559bd737572695be84c060..d3557ca5805063e1d072a3b59c345f85ad46db46 100644
--- a/src/pl/plpgsql/src/pl_comp.c
+++ b/src/pl/plpgsql/src/pl_comp.c
@@ -3,7 +3,7 @@
  *			  procedural language
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.91 2005/06/10 16:23:11 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.92 2005/07/06 16:42:10 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -547,6 +547,13 @@ do_compile(FunctionCallInfo fcinfo,
 			function->fn_retistuple = true;
 			function->fn_retset = false;
 
+			/* shouldn't be any declared arguments */
+			if (procStruct->pronargs != 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("trigger functions cannot have declared arguments"),
+						 errhint("You probably want to use TG_NARGS and TG_ARGV instead.")));
+
 			/* Add the record for referencing NEW */
 			rec = palloc0(sizeof(PLpgSQL_rec));
 			rec->dtype = PLPGSQL_DTYPE_REC;