diff --git a/src/dc_mimeparser.rs b/src/dc_mimeparser.rs
index c298017c3..6100553e5 100644
--- a/src/dc_mimeparser.rs
+++ b/src/dc_mimeparser.rs
@@ -1002,7 +1002,7 @@ impl<'a> MimeParser<'a> {
             unsafe {
                 let fld_message_id = (*field).fld_data.fld_message_id;
                 if !fld_message_id.is_null() {
-                    return Some(as_str((*fld_message_id).mid_value).to_string());
+                    return Some(to_string((*fld_message_id).mid_value));
                 }
             }
         }