diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 5b86185..00a8d19 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -6,6 +6,7 @@ Changelog
 - Enh #411: Standardization of Modal Button Positions
 - Enh #363: Deny access for files from message where current user is not participant
 - Fix #412: Fix active message after mark unread
+- Fix #15: When replying to a message, the conversation is marked as unread
 
 3.2.2 (July 9, 2024)
 --------------------
diff --git a/models/forms/ReplyForm.php b/models/forms/ReplyForm.php
index e21546d..e78c2b5 100644
--- a/models/forms/ReplyForm.php
+++ b/models/forms/ReplyForm.php
@@ -82,6 +82,14 @@ public function save()
             $this->reply->refresh(); // Update created_by date, otherwise db expression is set...
             $this->reply->notify();
             $this->reply->fileManager->attach(Yii::$app->request->post('fileList'));
+
+            // Update last viewed date to avoid marking the conversation as unread
+            $userMessage = $this->model->getUserMessage($this->reply->user_id);
+            if ($userMessage) {
+                $userMessage->last_viewed = date('Y-m-d G:i:s');
+                $userMessage->save();
+            }
+
             return true;
         }