diff -c -r postgresql-8.3.6.orig/src/pl/plpgsql/src/pl_exec.c postgresql-8.3.6/src/pl/plpgsql/src/pl_exec.c
*** postgresql-8.3.6.orig/src/pl/plpgsql/src/pl_exec.c	2009-02-27 09:25:38.000000000 +0000
--- postgresql-8.3.6/src/pl/plpgsql/src/pl_exec.c	2009-02-27 09:26:18.000000000 +0000
***************
*** 1088,1095 ****
--- 1088,1097 ----
  
  					free_var(state_var);
  					state_var->value = (Datum) 0;
+ 					state_var->isnull = true;
  					free_var(errm_var);
  					errm_var->value = (Datum) 0;
+ 					errm_var->isnull = true;
  					break;
  				}
  			}