diff --git a/src/dialog/dialog.rs b/src/dialog/dialog.rs
index 0a17f215..b1567064 100644
--- a/src/dialog/dialog.rs
+++ b/src/dialog/dialog.rs
@@ -361,9 +361,9 @@ impl DialogInner {
         }
         headers.push(Header::MaxForwards(70.into()));
 
-        body.as_ref().map(|b| {
-            headers.push(Header::ContentLength((b.len() as u32).into()));
-        });
+        headers.push(Header::ContentLength(
+            body.as_ref().map_or(0u32, |b| b.len() as u32).into(),
+        ));
 
         let req = rsip::Request {
             method,
@@ -454,9 +454,9 @@ impl DialogInner {
             .as_ref()
             .map(|c| resp_headers.push(Contact::from(c.clone()).into()));
 
-        body.as_ref().map(|b| {
-            resp_headers.push(Header::ContentLength((b.len() as u32).into()));
-        });
+        resp_headers.push(Header::ContentLength(
+            body.as_ref().map_or(0u32, |b| b.len() as u32).into(),
+        ));
 
         resp_headers.push(Header::UserAgent(
             self.endpoint_inner.user_agent.clone().into(),
diff --git a/src/transaction/message.rs b/src/transaction/message.rs
index c5289134..0d9ef214 100644
--- a/src/transaction/message.rs
+++ b/src/transaction/message.rs
@@ -226,10 +226,12 @@ impl EndpointInner {
                     | Header::CallId(_)
                     | Header::From(_)
                     | Header::To(_)
-                    | Header::MaxForwards(_)
                     | Header::CSeq(_)
             )
         });
+        headers.push(Header::ContentLength(
+            body.as_ref().map_or(0u32, |b| b.len() as u32).into(),
+        ));
         headers.unique_push(Header::UserAgent(self.user_agent.clone().into()));
         Response {
             status_code,
diff --git a/src/transport/tests/test_stream_encoding.rs b/src/transport/tests/test_stream_encoding.rs
index 9b7dedc1..a247f6c3 100644
--- a/src/transport/tests/test_stream_encoding.rs
+++ b/src/transport/tests/test_stream_encoding.rs
@@ -319,7 +319,7 @@ fn test_sip_codec_multiple_messages_with_bodies() {
             assert_eq!(req.call_id_header().unwrap().value(), "test-call-id-2");
         }
         _ => panic!("Expected request message"),
-    } 
+    }
 
     // Buffer should be empty after consuming both messages
     assert_eq!(
@@ -327,4 +327,4 @@ fn test_sip_codec_multiple_messages_with_bodies() {
         0,
         "Buffer should be empty after consuming all messages"
     );
-}
\ No newline at end of file
+}