diff --git a/app/src/main/java/eu/faircode/email/Core.java b/app/src/main/java/eu/faircode/email/Core.java
index 29c4c5b3a7..0e145d9507 100644
--- a/app/src/main/java/eu/faircode/email/Core.java
+++ b/app/src/main/java/eu/faircode/email/Core.java
@@ -6117,6 +6117,8 @@ class Core {
                 return true;
             if (!running)
                 return false;
+            if (thread == null)
+                return false;
             return thread.isAlive();
         }