diff --git a/model_server/clients/ilastik_map_objects.py b/model_server/clients/ilastik_map_objects.py
index d04a1fbc269d5624ba93e019ec042273b697f878..4fe5179171d0c70b00396f14e3b5cd5efbbecf7c 100644
--- a/model_server/clients/ilastik_map_objects.py
+++ b/model_server/clients/ilastik_map_objects.py
@@ -9,7 +9,7 @@ def main(request_func, in_abspath, params):
 	:param params:
 		pixel_classifier_path: (str) absolute path to ilastik project file that defines a pixel classifier
 		object_classifier_path: (str) absolute path to ilastik project file that defines an object classifier
-		channel: (int) channel of the input image to process
+		channel (optional): (int) channel of the input image to process, use all channels if not specified
 	:return: (str) absolute path where a new object map is written
 	"""
 
@@ -18,7 +18,7 @@ def main(request_func, in_abspath, params):
 	
 	px_ilp = params['pixel_classifier_path']
 	ob_ilp = params['object_classifier_path']
-	channel = params['channel']
+	channel = getattr(params, 'channel', None)
 	mip = params.get('mip', False)
 	
 	# configure input and output paths