diff --git a/generator/src/test/java/io/wcm/devops/conga/generator/util/FileUtilTest.java b/generator/src/test/java/io/wcm/devops/conga/generator/util/FileUtilTest.java
index 7b0b67c1..9996ca13 100644
--- a/generator/src/test/java/io/wcm/devops/conga/generator/util/FileUtilTest.java
+++ b/generator/src/test/java/io/wcm/devops/conga/generator/util/FileUtilTest.java
@@ -33,9 +33,12 @@ void testMatchesExtension() {
     assertTrue(FileUtil.matchesExtension(new File("test.txt"), "txt"));
     assertTrue(FileUtil.matchesExtension(new File("test.part2.txt"), "txt"));
     assertFalse(FileUtil.matchesExtension(new File("test.pdf"), "txt"));
+    assertTrue(FileUtil.matchesExtension(new File("test.json"), "json"));
 
     // special handling for OSGi configuration resource file extension
     assertTrue(FileUtil.matchesExtension(new File("test.cfg.json"), "cfg.json"));
+    assertFalse(FileUtil.matchesExtension(new File("test.cfg.json"), "json"));
+    assertFalse(FileUtil.matchesExtension(new File("test.json"), "cfg.json"));
   }
 
 }