1 files changed, 1 insertions, 1 deletions
diff --git a/luni/src/main/java/java/util/DuplicateFormatFlagsException.java b/luni/src/main/java/java/util/DuplicateFormatFlagsException.java
index d04db8e..2a2bc2e 100644
--- a/luni/src/main/java/java/util/DuplicateFormatFlagsException.java
+++ b/luni/src/main/java/java/util/DuplicateFormatFlagsException.java
@@ -37,7 +37,7 @@ public class DuplicateFormatFlagsException extends IllegalFormatException {
      */
     public DuplicateFormatFlagsException(String f) {
         if (f == null) {
-            throw new NullPointerException();
+            throw new NullPointerException("f == null");
         }
         flags = f;
     }