diff --git a/CHANGELOG-v3.md b/CHANGELOG-v3.md
index aad8919d570..d2c8c17a084 100644
--- a/CHANGELOG-v3.md
+++ b/CHANGELOG-v3.md
@@ -7,6 +7,9 @@
 - Craft.MatrixInput now fires an `afterInit` event after initialization. ([#3375](https://github.com/craftcms/cms/pull/3375))
 - Craft.MatrixInput now fires an `blockAdded` event after adding a new block. ([#3375](https://github.com/craftcms/cms/pull/3375))
 
+### Fixed
+- Fixed an error that could occur when acquiring a lock for a file path, if the `mutex` component was swapped out with `yii\mutex\MysqlMutex`.
+
 ## 3.0.27.1 - 2018-10-12
 
 ### Fixed
diff --git a/src/helpers/FileHelper.php b/src/helpers/FileHelper.php
index a1fdaeafa38..b1b6870b760 100644
--- a/src/helpers/FileHelper.php
+++ b/src/helpers/FileHelper.php
@@ -337,7 +337,11 @@ public static function writeToFile(string $file, string $contents, array $option
         }
 
         if ($lock) {
-            Craft::$app->getMutex()->acquire($file);
+            $mutex = Craft::$app->getMutex();
+            $lockName = md5($file);
+            $mutex->acquire($lockName);
+        } else {
+            $lockName = $mutex = null;
         }
 
         $flags = 0;
@@ -350,7 +354,7 @@ public static function writeToFile(string $file, string $contents, array $option
         }
 
         if ($lock) {
-            Craft::$app->getMutex()->release($file);
+            $mutex->release($lockName);
         }
     }