diff --git a/main/ui/src/main/java/org/cryptomator/ui/model/DokanyVolume.java b/main/ui/src/main/java/org/cryptomator/ui/model/DokanyVolume.java
index 667ff5ff9..35aff5bcb 100644
--- a/main/ui/src/main/java/org/cryptomator/ui/model/DokanyVolume.java
+++ b/main/ui/src/main/java/org/cryptomator/ui/model/DokanyVolume.java
@@ -1,9 +1,10 @@
 package org.cryptomator.ui.model;
 
 import javax.inject.Inject;
-import java.util.Iterator;
+import java.util.Set;
 import java.util.concurrent.ExecutorService;
 
+import com.google.common.collect.Sets;
 import org.cryptomator.common.settings.VaultSettings;
 import org.cryptomator.cryptofs.CryptoFileSystem;
 import org.cryptomator.frontend.dokany.Mount;
@@ -28,7 +29,7 @@ public class DokanyVolume implements Volume {
 
 	@Override
 	public boolean isSupported() {
-		return this.isSupportedStatic();
+		return DokanyVolume.isSupportedStatic();
 	}
 
 	//TODO: Drive letter 'A' as mount point is invalid in dokany. maybe we should do already here something against it
@@ -39,15 +40,10 @@ public class DokanyVolume implements Volume {
 			driveLetter = vaultSettings.winDriveLetter().get().charAt(0);
 		} else {
 			//auto assign drive letter
-			//TODO: can we assume the we have at least one free drive letter?
-
-			//this is a temporary fix for 'A' being an invalid drive letter
 			if (!windowsDriveLetters.getAvailableDriveLetters().isEmpty()) {
-				Iterator<Character> winDriveLetterIt = windowsDriveLetters.getAvailableDriveLetters().iterator();
-				do {
-					driveLetter = winDriveLetterIt.next();
-				} while (winDriveLetterIt.hasNext() && driveLetter == 65);
-//			if (!windowsDriveLetters.getAvailableDriveLetters().isEmpty()) {
+				//this is a temporary fix for 'A' being an invalid drive letter
+				Set<Character> availableLettersWithoutA = Sets.difference(windowsDriveLetters.getAvailableDriveLetters(), Set.of('A'));
+				driveLetter = availableLettersWithoutA.iterator().next();
 //				driveLetter = windowsDriveLetters.getAvailableDriveLetters().iterator().next();
 			} else {
 				throw new VolumeException("No free drive letter available.");
diff --git a/main/ui/src/main/java/org/cryptomator/ui/model/FuseVolume.java b/main/ui/src/main/java/org/cryptomator/ui/model/FuseVolume.java
index a11380ed1..ec63da443 100644
--- a/main/ui/src/main/java/org/cryptomator/ui/model/FuseVolume.java
+++ b/main/ui/src/main/java/org/cryptomator/ui/model/FuseVolume.java
@@ -118,7 +118,7 @@ public class FuseVolume implements Volume {
 
 	@Override
 	public boolean isSupported() {
-		return this.isSupportedStatic();
+		return FuseVolume.isSupportedStatic();
 	}
 
 	public static boolean isSupportedStatic() {
diff --git a/main/ui/src/main/java/org/cryptomator/ui/model/WebDavVolume.java b/main/ui/src/main/java/org/cryptomator/ui/model/WebDavVolume.java
index bbd201351..2161e388d 100644
--- a/main/ui/src/main/java/org/cryptomator/ui/model/WebDavVolume.java
+++ b/main/ui/src/main/java/org/cryptomator/ui/model/WebDavVolume.java
@@ -116,7 +116,7 @@ public class WebDavVolume implements Volume {
 
 	@Override
 	public boolean isSupported() {
-		return this.isSupportedStatic();
+		return WebDavVolume.isSupportedStatic();
 	}
 
 	@Override