diff --git a/main/commons/src/main/java/org/cryptomator/common/mountpoint/IrregularUnmountCleaner.java b/main/commons/src/main/java/org/cryptomator/common/mountpoint/IrregularUnmountCleaner.java
index 4e9866fda..6bcb36f9a 100644
--- a/main/commons/src/main/java/org/cryptomator/common/mountpoint/IrregularUnmountCleaner.java
+++ b/main/commons/src/main/java/org/cryptomator/common/mountpoint/IrregularUnmountCleaner.java
@@ -28,7 +28,7 @@ class IrregularUnmountCleaner {
 	}
 
 
-	public void clearIrregularUnmountDebrisIfNeeded() {
+	public synchronized void clearIrregularUnmountDebrisIfNeeded() {
 		if (alreadyChecked || tmpMountPointDir.isEmpty()) {
 			return; //nuthin to do
 		}