diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3ac5678a9..59c077291 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ accidentally triggering the load of a previous DB version.**
 * #3939 Fix projection handling in time_bucket_gapfill
 * #3979 Fix deparsing of index predicates
 * #4015 Eliminate float rounding instabilities in interpolate
+* #4020 Fix ALTER TABLE EventTrigger initialization
 
 **Thanks**
 * @erikhh for reporting an issue with time_bucket_gapfill
diff --git a/src/process_utility.c b/src/process_utility.c
index 8a4697ffc..6711a1896 100644
--- a/src/process_utility.c
+++ b/src/process_utility.c
@@ -3267,6 +3267,7 @@ process_altertable_start_table(ProcessUtilityArgs *args)
 				}
 				if (ht != NULL)
 				{
+					EventTriggerAlterTableStart(args->parsetree);
 					result = process_altertable_set_options(cmd, ht);
 				}
 				break;