diff --git a/NEWS b/NEWS
index c734e3bd9..e3c08055b 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,7 @@ Enhancements
 
 Bug fixes
  - [core] handle multi-valued mozillasecondemail attribute mapping
+ - [core] avoid displaying empty signed emails when using GNU TLS (#4433)
  - [web] improve popup window detection in message viewer (#4518)
 
 4.0.1 (2018-07-10)
diff --git a/UI/MailPartViewers/UIxMailPartSignedViewer.m b/UI/MailPartViewers/UIxMailPartSignedViewer.m
index 009736b21..9f00ba9c1 100644
--- a/UI/MailPartViewers/UIxMailPartSignedViewer.m
+++ b/UI/MailPartViewers/UIxMailPartSignedViewer.m
@@ -170,8 +170,9 @@
       if (err)
         {
           ERR_load_crypto_strings();
+          SSL_load_error_strings();
           sslError = ERR_reason_error_string(err);
-          validationMessage = [[self labelForKey: [NSString stringWithUTF8String: sslError]] retain];
+          validationMessage = [[self labelForKey: [NSString stringWithUTF8String: sslError ? sslError : "(no error information available)"]] retain];
         }
     }