diff --git a/main.tf b/main.tf
index cd50d15..64ac44d 100644
--- a/main.tf
+++ b/main.tf
@@ -108,6 +108,11 @@ resource "google_pubsub_subscription" "push_subscriptions" {
     "message_retention_duration",
     null,
   )
+  retain_acked_messages = lookup(
+    var.push_subscriptions[count.index],
+    "retain_acked_messages",
+    null,
+  )
   filter = lookup(
     var.push_subscriptions[count.index],
     "filter",
@@ -180,6 +185,11 @@ resource "google_pubsub_subscription" "pull_subscriptions" {
     "message_retention_duration",
     null,
   )
+  retain_acked_messages = lookup(
+    var.pull_subscriptions[count.index],
+    "retain_acked_messages",
+    null,
+  )
   filter = lookup(
     var.pull_subscriptions[count.index],
     "filter",