diff --git a/scrplugin/generator/src/main/java/org/apache/felix/scrplugin/JavaClassDescriptorManager.java b/scrplugin/generator/src/main/java/org/apache/felix/scrplugin/JavaClassDescriptorManager.java
index b1aa824..f4dce98 100644
--- a/scrplugin/generator/src/main/java/org/apache/felix/scrplugin/JavaClassDescriptorManager.java
+++ b/scrplugin/generator/src/main/java/org/apache/felix/scrplugin/JavaClassDescriptorManager.java
@@ -516,6 +516,10 @@
 
     private Manifest getManifest( File artifact ) throws IOException
     {
+        if ( artifact.isDirectory() )
+        {
+            return null;
+        }
         JarFile file = null;
         try
         {