diff --git a/src/test/regress/expected/create_procedure.out b/src/test/regress/expected/create_procedure.out
index dacb657706..66cdad760c 100644
--- a/src/test/regress/expected/create_procedure.out
+++ b/src/test/regress/expected/create_procedure.out
@@ -22,7 +22,7 @@ LINE 1: SELECT ptest1('x');
 HINT:  To call a procedure, use CALL.
 CALL ptest1('a');  -- ok
 CALL ptest1('xy' || 'zzy');  -- ok, constant-folded arg
-CALL ptest1(substring(random()::text, 1, 1));  -- ok, volatile arg
+CALL ptest1(substring(random()::numeric(20,15)::text, 1, 1));  -- ok, volatile arg
 \df ptest1
                         List of functions
  Schema |  Name  | Result data type | Argument data types | Type 
diff --git a/src/test/regress/sql/create_procedure.sql b/src/test/regress/sql/create_procedure.sql
index a6a935f578..1be9c6fd78 100644
--- a/src/test/regress/sql/create_procedure.sql
+++ b/src/test/regress/sql/create_procedure.sql
@@ -14,7 +14,7 @@ $$;
 SELECT ptest1('x');  -- error
 CALL ptest1('a');  -- ok
 CALL ptest1('xy' || 'zzy');  -- ok, constant-folded arg
-CALL ptest1(substring(random()::text, 1, 1));  -- ok, volatile arg
+CALL ptest1(substring(random()::numeric(20,15)::text, 1, 1));  -- ok, volatile arg
 
 \df ptest1
 SELECT pg_get_functiondef('ptest1'::regproc);