diff --git a/mx.py b/mx.py
index e65759ea..63733952 100755
--- a/mx.py
+++ b/mx.py
@@ -3059,10 +3059,10 @@ def netbeans_config_up_to_date(self, configZip):
         if configZip.isOlderThan(join(self.dir, 'build.xml')):
             return False
 
-        if configZip.isOlderThan(join(self.dir, 'nbproject/project.xml')):
+        if configZip.isOlderThan(join(self.dir, 'nbproject', 'project.xml')):
             return False
 
-        if configZip.isOlderThan(join(self.dir, 'nbproject/project.properties')):
+        if configZip.isOlderThan(join(self.dir, 'nbproject', 'project.properties')):
             return False
 
         return True