diff --git a/src/org/fdroid/fdroid/AppDetails.java b/src/org/fdroid/fdroid/AppDetails.java
index 47e240406..6e59a5c7d 100644
--- a/src/org/fdroid/fdroid/AppDetails.java
+++ b/src/org/fdroid/fdroid/AppDetails.java
@@ -412,7 +412,8 @@ public class AppDetails extends ListActivity {
     // Install the version of this app denoted by 'curapk'.
     private void install() {
 
-        if (mInstalledSigID != null && !curapk.sig.equals(mInstalledSigID)) {
+        if (mInstalledSigID != null && curapk.sig != null
+                && !curapk.sig.equals(mInstalledSigID)) {
             AlertDialog.Builder builder = new AlertDialog.Builder(this);
             builder.setMessage(R.string.SignatureMismatch).setPositiveButton(
                     "Ok", new DialogInterface.OnClickListener() {
diff --git a/src/org/fdroid/fdroid/SearchResults.java b/src/org/fdroid/fdroid/SearchResults.java
index 707cf8954..943044eae 100644
--- a/src/org/fdroid/fdroid/SearchResults.java
+++ b/src/org/fdroid/fdroid/SearchResults.java
@@ -20,18 +20,11 @@ package org.fdroid.fdroid;
 
 import java.util.Vector;
 
-import android.app.AlertDialog;
 import android.app.ListActivity;
 import android.app.SearchManager;
-import android.app.AlertDialog.Builder;
-import android.content.DialogInterface;
 import android.content.Intent;
-import android.content.pm.PackageInfo;
-import android.content.pm.PackageManager;
-import android.net.Uri;
 import android.os.Bundle;
 import android.util.Log;
-import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;