diff --git a/octoprint_bettergrblsupport/__init__.py b/octoprint_bettergrblsupport/__init__.py
index ea9cd1f..36141a0 100644
--- a/octoprint_bettergrblsupport/__init__.py
+++ b/octoprint_bettergrblsupport/__init__.py
@@ -434,9 +434,10 @@ def hook_gcode_sending(self, comm_instance, phase, cmd, cmd_type, gcode, *args,
 
             return self.helloCommand
 
-        # suppress comments
-        if cmd.upper().lstrip().startswith(';') or cmd.upper().lstrip().startswith('('):
-            self._logger.debug('Ignoring comment [%s]', cmd)
+        # suppress comments and extraneous commands that may cause wayward
+        # grbl instances to error out
+        if cmd.upper().lstrip().startswith(tuple([';', '(', '%'])):
+            self._logger.debug('Ignoring extraneous [%s]', cmd)
             return (None, )
 
         # suppress reset line #s
diff --git a/setup.py b/setup.py
index 12e9de3..c3c3716 100644
--- a/setup.py
+++ b/setup.py
@@ -14,7 +14,7 @@
 plugin_name = "Better Grbl Support"
 
 # The plugin's version. Can be overwritten within OctoPrint's internal data via __plugin_version__ in the plugin module
-plugin_version = "1.7.6dev1"
+plugin_version = "1.7.6dev2"
 
 # The plugin's description. Can be overwritten within OctoPrint's internal data via __plugin_description__ in the plugin
 # module