diff --git a/src/mimeparser.rs b/src/mimeparser.rs
index 2e811ebb9..2899a24f5 100644
--- a/src/mimeparser.rs
+++ b/src/mimeparser.rs
@@ -216,12 +216,12 @@ impl MimeMessage {
         headers.remove("secure-join-fingerprint");
         headers.remove("chat-verified");
 
-        let is_thunderbird = headers
-            .get("user-agent")
-            .map_or(false, |user_agent| user_agent.contains("Thunderbird"));
-        if is_thunderbird {
-            info!(context, "Detected Thunderbird");
-        }
+        let is_thunderbird = if let Some(user_agent) = headers.get("user-agent") {
+            info!(context, "Detected thunderbird");
+            user_agent.contains("Thunderbird")
+        } else {
+            false
+        };
 
         let from = from.context("No from in message")?;
         let mut decryption_info =