1 files changed, 2 insertions, 1 deletions
diff --git a/app/src/main/java/com/wireguard/android/widget/KeyInputFilter.java b/app/src/main/java/com/wireguard/android/widget/KeyInputFilter.java
index fff3bc22..a7c11717 100644
--- a/app/src/main/java/com/wireguard/android/widget/KeyInputFilter.java
+++ b/app/src/main/java/com/wireguard/android/widget/KeyInputFilter.java
@@ -6,6 +6,7 @@
 
 package com.wireguard.android.widget;
 
+import android.support.annotation.Nullable;
 import android.text.InputFilter;
 import android.text.SpannableStringBuilder;
 import android.text.Spanned;
@@ -25,7 +26,7 @@ public class KeyInputFilter implements InputFilter {
         return new KeyInputFilter();
     }
 
-    @Override
+    @Override @Nullable
     public CharSequence filter(final CharSequence source,
                                final int sStart, final int sEnd,
                                final Spanned dest,