diff --git a/src/runtime2/inbox.rs b/src/runtime2/inbox.rs
index 91db3a3711b6eecb1bfb71020328bbc54fad2f25..26983cc5a008de576fe4860a3c1e1b0fbf189777 100644
--- a/src/runtime2/inbox.rs
+++ b/src/runtime2/inbox.rs
@@ -127,6 +127,19 @@ pub(crate) enum Message {
     Control(ControlMessage),
 }
 
+impl Message {
+    /// If the message is sent through a particular channel, then this function
+    /// returns the port through which the message was sent.
+    pub(crate) fn source_port(&self) -> Option<PortIdLocal> {
+        // Currently only data messages have a source port
+        if let Message::Data(message) = self {
+            return Some(message.data_header.sending_port);
+        } else {
+            return None;
+        }
+    }
+}
+
 /// The public inbox of a connector. The thread running the connector that owns
 /// this inbox may retrieved from it. Non-owning threads may only put new
 /// messages inside of it.