diff --git a/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/ui/util/JavaProjectSetupUtil.java b/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/ui/util/JavaProjectSetupUtil.java
index 532a5672c..efcf5367f 100644
--- a/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/ui/util/JavaProjectSetupUtil.java
+++ b/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/ui/util/JavaProjectSetupUtil.java
@@ -374,6 +374,13 @@ public class JavaProjectSetupUtil {
 		addToClasspath(javaProject, newLibraryEntry);
 		return newLibraryEntry;
 	}
+	
+	public static IClasspathEntry addExternalJarToClasspath(IJavaProject javaProject, File file) throws JavaModelException {
+		IClasspathEntry newLibraryEntry = JavaCore.newLibraryEntry(new Path(file.getAbsolutePath()), null, null);
+		addToClasspath(javaProject, newLibraryEntry);
+		return newLibraryEntry;
+	}
+	
 
 	public static File createExternalJar(InputStream data, String nameWithoutJarSuffix) throws IOException,
 			FileNotFoundException {
diff --git a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/persistence/ResourceStorageFacade.xtend b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/persistence/ResourceStorageFacade.xtend
index 2bdd369a0..41a18a1f0 100644
--- a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/persistence/ResourceStorageFacade.xtend
+++ b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/resource/persistence/ResourceStorageFacade.xtend
@@ -94,6 +94,10 @@ class ResourceStorageFacade implements IResourceStorageFacade {
 		if (resource.resourceSet.URIConverter.exists(resource.URI.getBinaryStorageURI, emptyMap)) {
 			return true
 		}
+		// if it's an archive URI, we don't need to look up the source folder-output folder scheme
+		if (resource.URI.isArchive) {
+			return false
+		}
 		
 		// check for source project locations, i.e. use generator config
 		val fsa = getFileSystemAccess(resource);