diff --git a/test/org/mockitoutil/ClassLoaders.java b/test/org/mockitoutil/ClassLoaders.java
index 75c83507cd..e88b4935df 100644
--- a/test/org/mockitoutil/ClassLoaders.java
+++ b/test/org/mockitoutil/ClassLoaders.java
@@ -358,7 +358,8 @@ private boolean excludes(String qualifiedName, Set<String> packageFilters) {
         }
 
         private String classNameFor(File root, File file) {
-            String temp = file.getAbsolutePath().substring(root.getAbsolutePath().length() + 1).replace('/', '.');
+            String temp = file.getAbsolutePath().substring(root.getAbsolutePath().length() + 1).
+                    replace(File.separatorChar, '.');
             return temp.subSequence(0, temp.indexOf(".class")).toString();
         }