diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 8a9c0093c5..cc5eb73353 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.186 2007/01/30 18:02:22 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.187 2007/02/01 19:22:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -890,8 +890,27 @@ exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
 					{
 						if (var->default_val == NULL)
 						{
+							/* Initially it contains a NULL */
 							var->value = (Datum) 0;
 							var->isnull = true;
+							/*
+							 * If needed, give the datatype a chance to reject
+							 * NULLs, by assigning a NULL to the variable.
+							 * We claim the value is of type UNKNOWN, not the
+							 * var's datatype, else coercion will be skipped.
+							 * (Do this before the notnull check to be
+							 * consistent with exec_assign_value.)
+							 */
+							if (!var->datatype->typinput.fn_strict)
+							{
+								bool	valIsNull = true;
+
+								exec_assign_value(estate,
+												  (PLpgSQL_datum *) var,
+												  (Datum) 0,
+												  UNKNOWNOID,
+												  &valIsNull);
+							}
 							if (var->notnull)
 								ereport(ERROR,
 									(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
diff --git a/src/test/regress/expected/domain.out b/src/test/regress/expected/domain.out
index c4cad728b3..4acaaa4121 100644
--- a/src/test/regress/expected/domain.out
+++ b/src/test/regress/expected/domain.out
@@ -382,6 +382,22 @@ ERROR:  domain pos_int does not allow null values
 -- and local variables are enforced correctly.
 create function doubledecrement(p1 pos_int) returns pos_int as $$
 declare v pos_int;
+begin
+    return p1;
+end$$ language plpgsql;
+select doubledecrement(3); -- fail because of implicit null assignment
+ERROR:  domain pos_int does not allow null values
+CONTEXT:  PL/pgSQL function "doubledecrement" line 2 during statement block local variable initialization
+create or replace function doubledecrement(p1 pos_int) returns pos_int as $$
+declare v pos_int := 0;
+begin
+    return p1;
+end$$ language plpgsql;
+select doubledecrement(3); -- fail at initialization assignment
+ERROR:  value for domain pos_int violates check constraint "pos_int_check"
+CONTEXT:  PL/pgSQL function "doubledecrement" line 2 during statement block local variable initialization
+create or replace function doubledecrement(p1 pos_int) returns pos_int as $$
+declare v pos_int := 1;
 begin
     v := p1 - 1;
     return v - 1;
diff --git a/src/test/regress/sql/domain.sql b/src/test/regress/sql/domain.sql
index 21940e0e61..411d64648a 100644
--- a/src/test/regress/sql/domain.sql
+++ b/src/test/regress/sql/domain.sql
@@ -309,6 +309,22 @@ execute s1(NULL); -- should fail
 
 create function doubledecrement(p1 pos_int) returns pos_int as $$
 declare v pos_int;
+begin
+    return p1;
+end$$ language plpgsql;
+
+select doubledecrement(3); -- fail because of implicit null assignment
+
+create or replace function doubledecrement(p1 pos_int) returns pos_int as $$
+declare v pos_int := 0;
+begin
+    return p1;
+end$$ language plpgsql;
+
+select doubledecrement(3); -- fail at initialization assignment
+
+create or replace function doubledecrement(p1 pos_int) returns pos_int as $$
+declare v pos_int := 1;
 begin
     v := p1 - 1;
     return v - 1;