diff --git a/src/org/thialfihar/android/apg/Apg.java b/src/org/thialfihar/android/apg/Apg.java
index 8bb50f0f2..d2f37903a 100644
--- a/src/org/thialfihar/android/apg/Apg.java
+++ b/src/org/thialfihar/android/apg/Apg.java
@@ -648,6 +648,9 @@ public class Apg {
     }
 
     public static PGPPublicKey getMasterKey(PGPPublicKeyRing keyRing) {
+        if (keyRing == null) {
+            return null;
+        }
         for (PGPPublicKey key : new IterableIterator<PGPPublicKey>(keyRing.getPublicKeys())) {
             if (key.isMasterKey()) {
                 return key;
@@ -658,6 +661,9 @@ public class Apg {
     }
 
     public static PGPSecretKey getMasterKey(PGPSecretKeyRing keyRing) {
+        if (keyRing == null) {
+            return null;
+        }
         for (PGPSecretKey key : new IterableIterator<PGPSecretKey>(keyRing.getSecretKeys())) {
             if (key.isMasterKey()) {
                 return key;
diff --git a/src/org/thialfihar/android/apg/AskForSecretKeyPassPhrase.java b/src/org/thialfihar/android/apg/AskForSecretKeyPassPhrase.java
index 93078f235..01cd2de25 100644
--- a/src/org/thialfihar/android/apg/AskForSecretKeyPassPhrase.java
+++ b/src/org/thialfihar/android/apg/AskForSecretKeyPassPhrase.java
@@ -25,6 +25,7 @@ import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.Context;
 import android.content.DialogInterface;
+import android.content.DialogInterface.OnClickListener;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.widget.EditText;
@@ -42,6 +43,7 @@ public class AskForSecretKeyPassPhrase {
         alert.setTitle(R.string.title_authentification);
 
         final PGPSecretKey secretKey;
+        final Activity activity = context;
 
         if (secretKeyId == Id.key.symmetric || secretKeyId == Id.key.none) {
             secretKey = null;
@@ -49,7 +51,16 @@ public class AskForSecretKeyPassPhrase {
         } else {
             secretKey = Apg.getMasterKey(Apg.getSecretKeyRing(secretKeyId));
             if (secretKey == null) {
-                return null;
+                alert.setTitle(R.string.title_keyNotFound);
+                alert.setMessage(context.getString(R.string.keyNotFound, secretKeyId));
+                alert.setPositiveButton(android.R.string.ok, new OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        activity.removeDialog(Id.dialog.pass_phrase);
+                    }
+                });
+                alert.setCancelable(false);
+                return alert.create();
             }
             String userId = Apg.getMainUserIdSafe(context, secretKey);
             alert.setMessage(context.getString(R.string.passPhraseFor, userId));
@@ -65,7 +76,6 @@ public class AskForSecretKeyPassPhrase {
         alert.setView(view);
 
         final PassPhraseCallbackInterface cb = callback;
-        final Activity activity = context;
         alert.setPositiveButton(android.R.string.ok,
                 new DialogInterface.OnClickListener() {
                     public void onClick(DialogInterface dialog, int id) {