Index: trunk/quest-plugin-core/src/main/java/de/ugoe/cs/quest/plugin/PluginLoader.java
===================================================================
--- trunk/quest-plugin-core/src/main/java/de/ugoe/cs/quest/plugin/PluginLoader.java	(revision 772)
+++ trunk/quest-plugin-core/src/main/java/de/ugoe/cs/quest/plugin/PluginLoader.java	(revision 776)
@@ -126,6 +126,14 @@
 
 		JarInputStream jarInputStream = null;
+		Manifest manifest = null;
 		try {
-			jarInputStream = new JarInputStream(new FileInputStream(jarFile));
+		    FileInputStream fileStream = new FileInputStream(jarFile);
+		    try {
+		        jarInputStream = new JarInputStream(fileStream);
+		        manifest = jarInputStream.getManifest();
+		    } finally {
+		        jarInputStream.close();
+		        fileStream.close();
+		    }
 		} catch (FileNotFoundException e) {
 			throw new AssertionError(
@@ -134,6 +142,4 @@
 			throw new PluginLoaderException(e);
 		}
-
-		Manifest manifest = jarInputStream.getManifest();
 
 		String jarClassPath = manifest.getMainAttributes().getValue(