diff --git a/wlauto/utils/misc.py b/wlauto/utils/misc.py
index 40261ff8..121fac68 100644
--- a/wlauto/utils/misc.py
+++ b/wlauto/utils/misc.py
@@ -81,7 +81,7 @@ def check_output(command, timeout=None, ignore=None, **kwargs):
         ignore = []
     elif isinstance(ignore, int):
         ignore = [ignore]
-    elif not isinstance(ignore, list):
+    elif not isinstance(ignore, list) and ignore != 'all':
         message = 'Invalid value for ignore parameter: "{}"; must be an int or a list'
         raise ValueError(message.format(ignore))
     if 'stdout' in kwargs:
@@ -111,7 +111,7 @@ def check_output(command, timeout=None, ignore=None, **kwargs):
     if retcode:
         if retcode == -9:  # killed, assume due to timeout callback
             raise TimeoutError(command, output='\n'.join([output, error]))
-        elif retcode not in ignore:
+        elif ignore != 'all' and retcode not in ignore:
             raise subprocess.CalledProcessError(retcode, command, output='\n'.join([output, error]))
     return output, error
 
diff --git a/wlauto/workloads/telemetry/__init__.py b/wlauto/workloads/telemetry/__init__.py
index eb738598..2201841a 100644
--- a/wlauto/workloads/telemetry/__init__.py
+++ b/wlauto/workloads/telemetry/__init__.py
@@ -133,7 +133,7 @@ class Telemetry(Workload):
 
     def run(self, context):
         self.logger.debug(self.command)
-        self.raw_output, _ = check_output(self.command, shell=True, timeout=self.run_timeout, ignore=range(256))
+        self.raw_output, _ = check_output(self.command, shell=True, timeout=self.run_timeout, ignore='all')
 
     def update_result(self, context):  # pylint: disable=too-many-locals
         if not self.raw_output: