diff --git a/app/build.gradle b/app/build.gradle
index 49420e39..8785518a 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -17,8 +17,8 @@ android {
         minSdkVersion 14
         targetSdkVersion 22
 
-        versionCode 82
-        versionName "0.9.0.4"
+        versionCode 83
+        versionName "0.9.1"
 
         buildConfigField "java.util.Date", "buildTime", "new java.util.Date()"
     }
diff --git a/app/src/main/java/at/bitfire/davdroid/log/ExternalFileLogger.java b/app/src/main/java/at/bitfire/davdroid/log/ExternalFileLogger.java
index 07e61a3a..fd99c787 100644
--- a/app/src/main/java/at/bitfire/davdroid/log/ExternalFileLogger.java
+++ b/app/src/main/java/at/bitfire/davdroid/log/ExternalFileLogger.java
@@ -10,6 +10,8 @@ package at.bitfire.davdroid.log;
 
 import android.content.Context;
 
+import org.apache.commons.lang3.StringUtils;
+
 import java.io.Closeable;
 import java.io.File;
 import java.io.IOException;
@@ -24,7 +26,9 @@ public class ExternalFileLogger extends CustomLogger implements Closeable {
         if (dir == null)
             throw new IOException("External media not available for log creation");
 
-        File log = new File(dir, name = fileName);
+        name = StringUtils.remove(StringUtils.remove(fileName, File.pathSeparatorChar), File.separatorChar);
+
+        File log = new File(dir, name);
         writer = new PrintWriter(log);
     }