diff --git a/CHANGES b/CHANGES
index 51786367a7..a8ef6a31d0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,11 @@
 
+4.1.0-dev.404 | 2021-03-24 16:58:50 -0700
+
+  * Fix missing `user_agent` existence check in smtp/software.zeek (Michael Dopheide)
+
+    Without the check there can be extra reporter.log error noise, but
+    no actual difference in functionality.
+
 4.1.0-dev.402 | 2021-03-24 15:49:52 -0700
 
   * Add `bin_dir` setting for default zkg config file (Jon Siwek, Corelight)
diff --git a/VERSION b/VERSION
index 6513c5fba7..db2f2d0682 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.1.0-dev.402
+4.1.0-dev.404
diff --git a/scripts/policy/protocols/smtp/software.zeek b/scripts/policy/protocols/smtp/software.zeek
index 69cfdf4c57..342beedae0 100644
--- a/scripts/policy/protocols/smtp/software.zeek
+++ b/scripts/policy/protocols/smtp/software.zeek
@@ -48,7 +48,7 @@ export {
 
 event mime_one_header(c: connection, h: mime_header_rec) &priority=4
 	{
-	if ( ! c?$smtp ) return;
+	if ( ! c?$smtp || ! c$smtp?$user_agent ) return;
 	if ( h$name == "USER-AGENT" && webmail_user_agents in c$smtp$user_agent )
 		c$smtp$is_webmail = T;
 	}