diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c
index 02ab40eaac..b6894cbf76 100644
--- a/src/backend/commands/event_trigger.c
+++ b/src/backend/commands/event_trigger.c
@@ -1667,9 +1667,15 @@ EventTriggerAlterTableEnd(void)
 	/* If no subcommands, don't collect */
 	if (list_length(currentEventTriggerState->currentCommand->d.alterTable.subcmds) != 0)
 	{
+		MemoryContext oldcxt;
+
+		oldcxt = MemoryContextSwitchTo(currentEventTriggerState->cxt);
+
 		currentEventTriggerState->commandList =
 			lappend(currentEventTriggerState->commandList,
 					currentEventTriggerState->currentCommand);
+
+		MemoryContextSwitchTo(oldcxt);
 	}
 	else
 		pfree(currentEventTriggerState->currentCommand);
diff --git a/src/test/modules/test_extensions/Makefile b/src/test/modules/test_extensions/Makefile
index d18108e4e5..77ee4d5d9e 100644
--- a/src/test/modules/test_extensions/Makefile
+++ b/src/test/modules/test_extensions/Makefile
@@ -4,11 +4,13 @@ MODULE = test_extensions
 PGFILEDESC = "test_extensions - regression testing for EXTENSION support"
 
 EXTENSION = test_ext1 test_ext2 test_ext3 test_ext4 test_ext5 test_ext6 \
-            test_ext7 test_ext8 test_ext_cyclic1 test_ext_cyclic2
+            test_ext7 test_ext8 test_ext_cyclic1 test_ext_cyclic2 \
+            test_ext_evttrig
 DATA = test_ext1--1.0.sql test_ext2--1.0.sql test_ext3--1.0.sql \
        test_ext4--1.0.sql test_ext5--1.0.sql test_ext6--1.0.sql \
        test_ext7--1.0.sql test_ext7--1.0--2.0.sql test_ext8--1.0.sql \
-       test_ext_cyclic1--1.0.sql test_ext_cyclic2--1.0.sql
+       test_ext_cyclic1--1.0.sql test_ext_cyclic2--1.0.sql \
+       test_ext_evttrig--1.0.sql test_ext_evttrig--1.0--2.0.sql
 
 REGRESS = test_extensions test_extdepend
 
diff --git a/src/test/modules/test_extensions/expected/test_extensions.out b/src/test/modules/test_extensions/expected/test_extensions.out
index b5cbdfcad4..30ae621d05 100644
--- a/src/test/modules/test_extensions/expected/test_extensions.out
+++ b/src/test/modules/test_extensions/expected/test_extensions.out
@@ -154,3 +154,8 @@ DROP TABLE test_ext4_tab;
 DROP FUNCTION create_extension_with_temp_schema();
 RESET client_min_messages;
 \unset SHOW_CONTEXT
+-- Test case of an event trigger run in an extension upgrade script.
+-- See: https://postgr.es/m/20200902193715.6e0269d4@firost
+CREATE EXTENSION test_ext_evttrig;
+ALTER EXTENSION test_ext_evttrig UPDATE TO '2.0';
+DROP EXTENSION test_ext_evttrig;
diff --git a/src/test/modules/test_extensions/sql/test_extensions.sql b/src/test/modules/test_extensions/sql/test_extensions.sql
index f505466ab4..c16fd36da8 100644
--- a/src/test/modules/test_extensions/sql/test_extensions.sql
+++ b/src/test/modules/test_extensions/sql/test_extensions.sql
@@ -93,3 +93,9 @@ DROP TABLE test_ext4_tab;
 DROP FUNCTION create_extension_with_temp_schema();
 RESET client_min_messages;
 \unset SHOW_CONTEXT
+
+-- Test case of an event trigger run in an extension upgrade script.
+-- See: https://postgr.es/m/20200902193715.6e0269d4@firost
+CREATE EXTENSION test_ext_evttrig;
+ALTER EXTENSION test_ext_evttrig UPDATE TO '2.0';
+DROP EXTENSION test_ext_evttrig;
diff --git a/src/test/modules/test_extensions/test_ext_evttrig--1.0--2.0.sql b/src/test/modules/test_extensions/test_ext_evttrig--1.0--2.0.sql
new file mode 100644
index 0000000000..fdd2f3542e
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_evttrig--1.0--2.0.sql
@@ -0,0 +1,7 @@
+/* src/test/modules/test_extensions/test_event_trigger--1.0--2.0.sql */
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION test_event_trigger UPDATE TO '2.0'" to load this file. \quit
+
+-- Test extension upgrade with event trigger.
+ALTER EVENT TRIGGER table_rewrite_trg DISABLE;
+ALTER TABLE t DROP COLUMN id;
diff --git a/src/test/modules/test_extensions/test_ext_evttrig--1.0.sql b/src/test/modules/test_extensions/test_ext_evttrig--1.0.sql
new file mode 100644
index 0000000000..0071712cb8
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_evttrig--1.0.sql
@@ -0,0 +1,16 @@
+/* src/test/modules/test_extensions/test_event_trigger--1.0.sql */
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_event_trigger" to load this file. \quit
+
+-- Base table with event trigger, used in a regression test involving
+-- extension upgrades.
+CREATE TABLE t (id text);
+CREATE OR REPLACE FUNCTION _evt_table_rewrite_fnct()
+RETURNS EVENT_TRIGGER LANGUAGE plpgsql AS
+$$
+  BEGIN
+  END;
+$$;
+CREATE EVENT TRIGGER table_rewrite_trg
+  ON table_rewrite
+  EXECUTE PROCEDURE _evt_table_rewrite_fnct();
diff --git a/src/test/modules/test_extensions/test_ext_evttrig.control b/src/test/modules/test_extensions/test_ext_evttrig.control
new file mode 100644
index 0000000000..915fae6166
--- /dev/null
+++ b/src/test/modules/test_extensions/test_ext_evttrig.control
@@ -0,0 +1,3 @@
+comment = 'Test extension - event trigger'
+default_version = '1.0'
+relocatable = true