diff --git a/src/main/java/eu/siacs/conversations/services/AvatarService.java b/src/main/java/eu/siacs/conversations/services/AvatarService.java
index fc1ed28ea..b8154d655 100644
--- a/src/main/java/eu/siacs/conversations/services/AvatarService.java
+++ b/src/main/java/eu/siacs/conversations/services/AvatarService.java
@@ -58,9 +58,11 @@ public class AvatarService {
 	}
 
 	public void clear(Contact contact) {
-		for (Integer size : sizes) {
-			this.mXmppConnectionService.getBitmapCache().remove(
-					key(contact, size));
+		synchronized (this.sizes) {
+			for (Integer size : sizes) {
+				this.mXmppConnectionService.getBitmapCache().remove(
+						key(contact, size));
+			}
 		}
 	}
 
@@ -150,9 +152,11 @@ public class AvatarService {
 	}
 
 	public void clear(MucOptions options) {
-		for (Integer size : sizes) {
-			this.mXmppConnectionService.getBitmapCache().remove(
-					key(options, size));
+		synchronized (this.sizes) {
+			for (Integer size : sizes) {
+				this.mXmppConnectionService.getBitmapCache().remove(
+						key(options, size));
+			}
 		}
 	}
 
@@ -182,9 +186,11 @@ public class AvatarService {
 	}
 
 	public void clear(Account account) {
-		for (Integer size : sizes) {
-			this.mXmppConnectionService.getBitmapCache().remove(
-					key(account, size));
+		synchronized (this.sizes) {
+			for (Integer size : sizes) {
+				this.mXmppConnectionService.getBitmapCache().remove(
+						key(account, size));
+			}
 		}
 	}
 
diff --git a/src/main/res/menu/muc_details_context.xml b/src/main/res/menu/muc_details_context.xml
new file mode 100644
index 000000000..fe187c0cf
--- /dev/null
+++ b/src/main/res/menu/muc_details_context.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+
+</menu>
\ No newline at end of file