diff --git a/bacnet-stack/include/dlmstp.h b/bacnet-stack/include/dlmstp.h
index 63f3455c..da200149 100644
--- a/bacnet-stack/include/dlmstp.h
+++ b/bacnet-stack/include/dlmstp.h
@@ -122,6 +122,8 @@ extern "C" {
         BACNET_ADDRESS * src,
         uint8_t mstp_address);
 
+    bool dlmstp_sole_master(void);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */