diff --git a/mbus/mbus-serial.c b/mbus/mbus-serial.c
index f5aa052..ec6b112 100644
--- a/mbus/mbus-serial.c
+++ b/mbus/mbus-serial.c
@@ -226,7 +226,10 @@ mbus_serial_recv_frame(mbus_serial_handle *handle, mbus_frame *frame)
     int len, remaining, nread;
     
     if (handle == NULL || frame == NULL)
+    {
+        fprintf(stderr, "%s: Invalid parameter.\n", __PRETTY_FUNCTION__);
         return -1;
+    }
 
     memset((void *)buff, 0, sizeof(buff));
 
diff --git a/mbus/mbus-tcp.c b/mbus/mbus-tcp.c
index e820090..17150fb 100644
--- a/mbus/mbus-tcp.c
+++ b/mbus/mbus-tcp.c
@@ -168,7 +168,10 @@ mbus_tcp_recv_frame(mbus_tcp_handle *handle, mbus_frame *frame)
     int len, remaining, nread;
     
     if (handle == NULL || frame == NULL)
+    {
+        fprintf(stderr, "%s: Invalid parameter.\n", __PRETTY_FUNCTION__);
         return -1;
+    }
 
     memset((void *)buff, 0, sizeof(buff));