diff --git a/compiler/core/src/zserio/tools/ExtensionManager.java b/compiler/core/src/zserio/tools/ExtensionManager.java
index 0d0534366..f0157c377 100644
--- a/compiler/core/src/zserio/tools/ExtensionManager.java
+++ b/compiler/core/src/zserio/tools/ExtensionManager.java
@@ -6,6 +6,7 @@
 import java.io.StringWriter;
 import java.io.UnsupportedEncodingException;
 import java.net.MalformedURLException;
+import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.net.URLDecoder;
@@ -105,11 +106,11 @@ public void callExtensions(Root rootNode, ExtensionParameters parameters) throws
     private ClassLoader getClassLoader()
     {
         final ClassLoader currentClassLoader = getClass().getClassLoader();
-        final String workingDirectory = getWorkingDirectory();
+        final File workingDirectory = getWorkingDirectory();
         if (workingDirectory == null)
             return currentClassLoader;
 
-        final File[] fileList = new File(workingDirectory).listFiles();
+        final File[] fileList = workingDirectory.listFiles();
         if (fileList == null)
             return currentClassLoader;
 
@@ -136,17 +137,19 @@ private ClassLoader getClassLoader()
         return urlClassLoader;
     }
 
-    private String getWorkingDirectory()
+    private File getWorkingDirectory()
     {
         try
         {
             final String execPath = getClass().getProtectionDomain().getCodeSource().getLocation().getPath();
             final String decodedExecPath = URLDecoder.decode(execPath, "UTF-8");
-            final String workingDirectory = new File(decodedExecPath).getParent();
+            final String workingDirectoryUrl = new File(decodedExecPath).getParent();
+            final File workingDirectory = new File(new URL(workingDirectoryUrl).toURI());
 
             return workingDirectory;
         }
-        catch (SecurityException | UnsupportedEncodingException excpt)
+        catch (SecurityException | UnsupportedEncodingException | MalformedURLException |
+                URISyntaxException excpt)
         {
             return null;
         }