diff --git a/src/mm-port.c b/src/mm-port.c
index 667b3fc4..a1291d0b 100644
--- a/src/mm-port.c
+++ b/src/mm-port.c
@@ -46,6 +46,20 @@ typedef struct {
 
 /*****************************************************************************/
 
+const char *
+mm_port_subsys_to_name (MMPortSubsys psubsys)
+{
+    switch (psubsys) {
+    case MM_PORT_SUBSYS_TTY:
+        return "tty";
+    case MM_PORT_SUBSYS_NET:
+        return "net";
+    default:
+        break;
+    }
+    return "(unknown)";
+}
+
 const char *
 mm_port_type_to_name (MMPortType ptype)
 {
diff --git a/src/mm-port.h b/src/mm-port.h
index 43f78f46..4bcffd49 100644
--- a/src/mm-port.h
+++ b/src/mm-port.h
@@ -78,5 +78,7 @@ void         mm_port_set_connected      (MMPort *self, gboolean connected);
 
 const char * mm_port_type_to_name       (MMPortType ptype);
 
+const char * mm_port_subsys_to_name     (MMPortSubsys psubsys);
+
 #endif /* MM_PORT_H */