diff --git a/playbooks/roles/gerrit/templates/gerrit.config.j2 b/playbooks/roles/gerrit/templates/gerrit.config.j2
index 46516437d5..7e15121029 100644
--- a/playbooks/roles/gerrit/templates/gerrit.config.j2
+++ b/playbooks/roles/gerrit/templates/gerrit.config.j2
@@ -80,6 +80,8 @@
 	allowDrafts = false
 	disablePrivateChanges = true
 	move = false
+# Keep pre-3.4 behavior
+	mergeabilityComputationBehavior = API_REF_UPDATED_AND_CHANGE_REINDEX
 [receive]
 	maxObjectSizeLimit = 100 m
 	enableSignedPush = false