diff --git a/Marlin/Marlin.pde b/Marlin/Marlin.pde
index 824a57d780..bbef8170d7 100644
--- a/Marlin/Marlin.pde
+++ b/Marlin/Marlin.pde
@@ -864,6 +864,8 @@ FORCE_INLINE void process_commands()
               {
                  SERIAL_PROTOCOLLN( "?" );
               }
+            #else
+              SERIAL_PROTOCOLLN("");
             #endif
             codenum = millis();
           }