diff --git a/CHANGELOG.md b/CHANGELOG.md
index 06565d342..43d9ef75d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
+ - Fix `message_retention_duration` variable type in `pubsub` module 
 
 ## [4.9.0] - 2021-06-04
 
diff --git a/modules/pubsub/README.md b/modules/pubsub/README.md
index 868f693f0..938f27166 100644
--- a/modules/pubsub/README.md
+++ b/modules/pubsub/README.md
@@ -96,14 +96,14 @@ module "pubsub" {
 | name | PubSub topic name. | <code title="">string</code> | ✓ |  |
 | project_id | Project used for resources. | <code title="">string</code> | ✓ |  |
 | *dead_letter_configs* | Per-subscription dead letter policy configuration. | <code title="map&#40;object&#40;&#123;&#10;topic                &#61; string&#10;max_delivery_attemps &#61; number&#10;&#125;&#41;&#41;">map(object({...}))</code> |  | <code title="">{}</code> |
-| *defaults* | Subscription defaults for options. | <code title="object&#40;&#123;&#10;ack_deadline_seconds       &#61; number&#10;message_retention_duration &#61; number&#10;retain_acked_messages      &#61; bool&#10;expiration_policy_ttl      &#61; string&#10;&#125;&#41;">object({...})</code> |  | <code title="&#123;&#10;ack_deadline_seconds       &#61; null&#10;message_retention_duration &#61; null&#10;retain_acked_messages      &#61; null&#10;expiration_policy_ttl      &#61; null&#10;&#125;">...</code> |
+| *defaults* | Subscription defaults for options. | <code title="object&#40;&#123;&#10;ack_deadline_seconds       &#61; number&#10;message_retention_duration &#61; string&#10;retain_acked_messages      &#61; bool&#10;expiration_policy_ttl      &#61; string&#10;&#125;&#41;">object({...})</code> |  | <code title="&#123;&#10;ack_deadline_seconds       &#61; null&#10;message_retention_duration &#61; null&#10;retain_acked_messages      &#61; null&#10;expiration_policy_ttl      &#61; null&#10;&#125;">...</code> |
 | *iam* | IAM bindings for topic in {ROLE => [MEMBERS]} format. | <code title="map&#40;list&#40;string&#41;&#41;">map(list(string))</code> |  | <code title="">{}</code> |
 | *kms_key* | KMS customer managed encryption key. | <code title="">string</code> |  | <code title="">null</code> |
 | *labels* | Labels. | <code title="map&#40;string&#41;">map(string)</code> |  | <code title="">{}</code> |
 | *push_configs* | Push subscription configurations. | <code title="map&#40;object&#40;&#123;&#10;attributes &#61; map&#40;string&#41;&#10;endpoint   &#61; string&#10;oidc_token &#61; object&#40;&#123;&#10;audience              &#61; string&#10;service_account_email &#61; string&#10;&#125;&#41;&#10;&#125;&#41;&#41;">map(object({...}))</code> |  | <code title="">{}</code> |
 | *regions* | List of regions used to set persistence policy. | <code title="list&#40;string&#41;">list(string)</code> |  | <code title="">[]</code> |
 | *subscription_iam* | IAM bindings for subscriptions in {SUBSCRIPTION => {ROLE => [MEMBERS]}} format. | <code title="map&#40;map&#40;list&#40;string&#41;&#41;&#41;">map(map(list(string)))</code> |  | <code title="">{}</code> |
-| *subscriptions* | Topic subscriptions. Also define push configs for push subscriptions. If options is set to null subscription defaults will be used. Labels default to topic labels if set to null. | <code title="map&#40;object&#40;&#123;&#10;labels &#61; map&#40;string&#41;&#10;options &#61; object&#40;&#123;&#10;ack_deadline_seconds       &#61; number&#10;message_retention_duration &#61; number&#10;retain_acked_messages      &#61; bool&#10;expiration_policy_ttl      &#61; string&#10;&#125;&#41;&#10;&#125;&#41;&#41;">map(object({...}))</code> |  | <code title="">{}</code> |
+| *subscriptions* | Topic subscriptions. Also define push configs for push subscriptions. If options is set to null subscription defaults will be used. Labels default to topic labels if set to null. | <code title="map&#40;object&#40;&#123;&#10;labels &#61; map&#40;string&#41;&#10;options &#61; object&#40;&#123;&#10;ack_deadline_seconds       &#61; number&#10;message_retention_duration &#61; string&#10;retain_acked_messages      &#61; bool&#10;expiration_policy_ttl      &#61; string&#10;&#125;&#41;&#10;&#125;&#41;&#41;">map(object({...}))</code> |  | <code title="">{}</code> |
 
 ## Outputs
 
diff --git a/modules/pubsub/variables.tf b/modules/pubsub/variables.tf
index b76d3c117..6657d4354 100644
--- a/modules/pubsub/variables.tf
+++ b/modules/pubsub/variables.tf
@@ -27,7 +27,7 @@ variable "defaults" {
   description = "Subscription defaults for options."
   type = object({
     ack_deadline_seconds       = number
-    message_retention_duration = number
+    message_retention_duration = string
     retain_acked_messages      = bool
     expiration_policy_ttl      = string
   })
@@ -93,7 +93,7 @@ variable "subscriptions" {
     labels = map(string)
     options = object({
       ack_deadline_seconds       = number
-      message_retention_duration = number
+      message_retention_duration = string
       retain_acked_messages      = bool
       expiration_policy_ttl      = string
     })