--- a/Tools__NewSystemBrowser.st	Thu Jan 12 10:07:28 2017 +0100
+++ b/Tools__NewSystemBrowser.st	Thu Jan 12 10:09:12 2017 +0100
@@ -29470,9 +29470,21 @@
 
     |fileBrowser dir fn|
 
+    aClass package == PackageId noProjectID ifTrue:[
+        Dialog warn:'No project directory (the class is not assigned to any package).'.
+        ^ self.
+    ].
+    
     fileBrowser := UserPreferences fileBrowserClass.
 
     dir := aClass theNonMetaclass packageDirectory.
+    dir isNil ifTrue:[
+        dir := Smalltalk packageDirectoryForPackageId:aClass package.
+        dir isNil ifTrue:[
+            Dialog warn:'No project directory (the class is not assigned to any package).'.
+            ^ self.
+        ].    
+    ].    
     (dir asFilename exists and:[(fn := dir / aClass classFilename) exists]) ifTrue:[
         fileBrowser openOn:fn
     ] ifFalse:[