diff --git a/app/src/main/java/eu/faircode/email/InternetAddressJson.java b/app/src/main/java/eu/faircode/email/InternetAddressJson.java
index d1f65e629c..1e8d6250b6 100644
--- a/app/src/main/java/eu/faircode/email/InternetAddressJson.java
+++ b/app/src/main/java/eu/faircode/email/InternetAddressJson.java
@@ -98,7 +98,7 @@ public class InternetAddressJson extends InternetAddress {
         super.validate();
     }
 
-    private void ensureParsed() {
+    private synchronized void ensureParsed() {
         if (this.json != null) {
             try {
                 String email = json.getString("address");