diff --git a/app/src/main/java/org/linphone/call/CallActivity.java b/app/src/main/java/org/linphone/call/CallActivity.java
index 53e13efa7..68cb70b14 100644
--- a/app/src/main/java/org/linphone/call/CallActivity.java
+++ b/app/src/main/java/org/linphone/call/CallActivity.java
@@ -1174,7 +1174,7 @@ public class CallActivity extends LinphoneGenericActivity implements OnClickList
 
         if (status != null && lc != null) {
             Call currentCall = lc.getCurrentCall();
-            if (!currentCall.getAuthenticationTokenVerified()) {
+            if (currentCall != null && !currentCall.getAuthenticationTokenVerified()) {
                 status.showZRTPDialog(currentCall);
             }
         }
diff --git a/app/src/main/java/org/linphone/chat/ChatEventsAdapter.java b/app/src/main/java/org/linphone/chat/ChatEventsAdapter.java
index b237ed351..6b829424a 100644
--- a/app/src/main/java/org/linphone/chat/ChatEventsAdapter.java
+++ b/app/src/main/java/org/linphone/chat/ChatEventsAdapter.java
@@ -30,7 +30,6 @@ import android.graphics.Matrix;
 import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.media.ExifInterface;
-import android.media.ThumbnailUtils;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.provider.MediaStore;
@@ -420,6 +419,9 @@ public class ChatEventsAdapter extends SelectableAdapter<ChatBubbleViewHolder> {
                         case ParticipantMaxDeviceCountExceeded:
                             holder.eventMessage.setText(mContext.getString(R.string.participant_max_count_exceeded).replace("%s", displayName));
                             break;
+                        case None:
+                        default:
+                            break;
                     }
                     break;
                 case None:
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 9a4163a4f..e6a30918e 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.7-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists