diff --git a/src/main/java/eu/siacs/conversations/services/MemorizingTrustManager.java b/src/main/java/eu/siacs/conversations/services/MemorizingTrustManager.java
index 9f2a5de36..e94c1c5c0 100644
--- a/src/main/java/eu/siacs/conversations/services/MemorizingTrustManager.java
+++ b/src/main/java/eu/siacs/conversations/services/MemorizingTrustManager.java
@@ -619,7 +619,7 @@ public class MemorizingTrustManager {
 
     private X509Certificate[] getAcceptedIssuers() {
         LOGGER.log(Level.FINE, "getAcceptedIssuers()");
-        return defaultTrustManager.getAcceptedIssuers();
+        return defaultTrustManager == null ? new X509Certificate[0] : defaultTrustManager.getAcceptedIssuers();
     }
 
     private int createDecisionId(MTMDecision d) {