diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 1f2abbb5d1..f8c6435c50 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3849,7 +3849,7 @@ ASSERT <replaceable class="parameter">condition</replaceable> <optional> , <repl
       <para>
        Data type <type>RECORD</type>; variable holding the new
        database row for <command>INSERT</command>/<command>UPDATE</command> operations in row-level
-       triggers. This variable is unassigned in statement-level triggers
+       triggers. This variable is null in statement-level triggers
        and for <command>DELETE</command> operations.
       </para>
      </listitem>
@@ -3861,7 +3861,7 @@ ASSERT <replaceable class="parameter">condition</replaceable> <optional> , <repl
       <para>
        Data type <type>RECORD</type>; variable holding the old
        database row for <command>UPDATE</command>/<command>DELETE</command> operations in row-level
-       triggers. This variable is unassigned in statement-level triggers
+       triggers. This variable is null in statement-level triggers
        and for <command>INSERT</command> operations.
       </para>
      </listitem>
diff --git a/doc/src/sgml/release-11.sgml b/doc/src/sgml/release-11.sgml
index f35b0d8cc9..b129d32264 100644
--- a/doc/src/sgml/release-11.sgml
+++ b/doc/src/sgml/release-11.sgml
@@ -1033,6 +1033,23 @@ Branch: REL9_3_STABLE [84261eb10] 2018-10-19 17:02:26 -0400
        </para>
       </listitem>
 
+      <listitem>
+<!--
+2018-02-13 [4b93f5799] Make plpgsql use its DTYPE_REC code paths for composite-
+-->
+
+       <para>
+        In PL/pgSQL trigger functions, the <varname>OLD</varname>
+        and <varname>NEW</varname> variables now read as NULL when not
+        assigned (Tom Lane)
+       </para>
+
+       <para>
+        Previously, references to these variables could be parsed but not
+        executed.
+       </para>
+      </listitem>
+
    </itemizedlist>
 
   </sect2>
@@ -2574,7 +2591,6 @@ same commits as above
       <listitem>
 <!--
 2018-02-13 [4b93f5799] Make plpgsql use its DTYPE_REC code paths for composite-
-
 -->
 
        <para>
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 9dd4a74c34..f5958d1267 100644
--- a/src/pl/plpgsql/src/Makefile
+++ b/src/pl/plpgsql/src/Makefile
@@ -27,7 +27,7 @@ DATA = plpgsql.control plpgsql--1.0.sql plpgsql--unpackaged--1.0.sql
 REGRESS_OPTS = --dbname=$(PL_TESTDB)
 
 REGRESS = plpgsql_call plpgsql_control plpgsql_domain plpgsql_record \
-	plpgsql_cache plpgsql_transaction plpgsql_varprops
+	plpgsql_cache plpgsql_transaction plpgsql_trigger plpgsql_varprops
 
 GEN_KEYWORDLIST = $(top_srcdir)/src/tools/gen_keywordlist.pl
 
diff --git a/src/pl/plpgsql/src/expected/plpgsql_trigger.out b/src/pl/plpgsql/src/expected/plpgsql_trigger.out
new file mode 100644
index 0000000000..3cc67badba
--- /dev/null
+++ b/src/pl/plpgsql/src/expected/plpgsql_trigger.out
@@ -0,0 +1,36 @@
+-- Simple test to verify accessibility of the OLD and NEW trigger variables
+create table testtr (a int, b text);
+create function testtr_trigger() returns trigger language plpgsql as
+$$begin
+  raise notice 'tg_op = %', tg_op;
+  raise notice 'old(%) = %', old.a, row(old.*);
+  raise notice 'new(%) = %', new.a, row(new.*);
+  if (tg_op = 'DELETE') then
+    return old;
+  else
+    return new;
+  end if;
+end$$;
+create trigger testtr_trigger before insert or delete or update on testtr
+  for each row execute function testtr_trigger();
+insert into testtr values (1, 'one'), (2, 'two');
+NOTICE:  tg_op = INSERT
+NOTICE:  old(<NULL>) = (,)
+NOTICE:  new(1) = (1,one)
+NOTICE:  tg_op = INSERT
+NOTICE:  old(<NULL>) = (,)
+NOTICE:  new(2) = (2,two)
+update testtr set a = a + 1;
+NOTICE:  tg_op = UPDATE
+NOTICE:  old(1) = (1,one)
+NOTICE:  new(2) = (2,one)
+NOTICE:  tg_op = UPDATE
+NOTICE:  old(2) = (2,two)
+NOTICE:  new(3) = (3,two)
+delete from testtr;
+NOTICE:  tg_op = DELETE
+NOTICE:  old(2) = (2,one)
+NOTICE:  new(<NULL>) = (,)
+NOTICE:  tg_op = DELETE
+NOTICE:  old(3) = (3,two)
+NOTICE:  new(<NULL>) = (,)
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 92e7ec4c60..5c6dbe4c5f 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -891,11 +891,12 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
 	/*
 	 * Put the OLD and NEW tuples into record variables
 	 *
-	 * We make the tupdescs available in both records even though only one may
-	 * have a value.  This allows parsing of record references to succeed in
-	 * functions that are used for multiple trigger types.  For example, we
-	 * might have a test like "if (TG_OP = 'INSERT' and NEW.foo = 'xyz')",
-	 * which should parse regardless of the current trigger type.
+	 * We set up expanded records for both variables even though only one may
+	 * have a value.  This allows record references to succeed in functions
+	 * that are used for multiple trigger types.  For example, we might have a
+	 * test like "if (TG_OP = 'INSERT' and NEW.foo = 'xyz')", which should
+	 * work regardless of the current trigger type.  If a value is actually
+	 * fetched from an unsupplied tuple, it will read as NULL.
 	 */
 	tupdesc = RelationGetDescr(trigdata->tg_relation);
 
diff --git a/src/pl/plpgsql/src/sql/plpgsql_trigger.sql b/src/pl/plpgsql/src/sql/plpgsql_trigger.sql
new file mode 100644
index 0000000000..e04c273c51
--- /dev/null
+++ b/src/pl/plpgsql/src/sql/plpgsql_trigger.sql
@@ -0,0 +1,24 @@
+-- Simple test to verify accessibility of the OLD and NEW trigger variables
+
+create table testtr (a int, b text);
+
+create function testtr_trigger() returns trigger language plpgsql as
+$$begin
+  raise notice 'tg_op = %', tg_op;
+  raise notice 'old(%) = %', old.a, row(old.*);
+  raise notice 'new(%) = %', new.a, row(new.*);
+  if (tg_op = 'DELETE') then
+    return old;
+  else
+    return new;
+  end if;
+end$$;
+
+create trigger testtr_trigger before insert or delete or update on testtr
+  for each row execute function testtr_trigger();
+
+insert into testtr values (1, 'one'), (2, 'two');
+
+update testtr set a = a + 1;
+
+delete from testtr;