diff --git a/build/entrypoint.sh b/build/entrypoint.sh
index 1931087..f9ce1bc 100644
--- a/build/entrypoint.sh
+++ b/build/entrypoint.sh
@@ -23,8 +23,8 @@ else
     # socat will make the conn appear to come from 127.0.0.1
     # ProtonMail Bridge currently expects that.
     # It also allows us to bind to the real ports :)
-    socat TCP-LISTEN:25,fork TCP:127.0.0.1:1025 &
-    socat TCP-LISTEN:143,fork TCP:127.0.0.1:1143 &
+    socat TCP6-LISTEN:25,fork TCP:127.0.0.1:1025 &
+    socat TCP6-LISTEN:143,fork TCP:127.0.0.1:1143 &
 
     # Start protonmail
     # Fake a terminal, so it does not quit because of EOF...