diff --git a/src/main/java/org/jboss/jandex/Main.java b/src/main/java/org/jboss/jandex/Main.java
index f70fc8d8..c4c49159 100644
--- a/src/main/java/org/jboss/jandex/Main.java
+++ b/src/main/java/org/jboss/jandex/Main.java
@@ -139,6 +139,9 @@ private void scanFile(File source, Indexer indexer) throws FileNotFoundException
             return;
         }
 
+        if (! source.getName().endsWith(".class"))
+            return;
+
         FileInputStream input = new FileInputStream(source);
 
         try {