diff --git a/Tests/test_imageshow.py b/Tests/test_imageshow.py
index 832546be5..22658780e 100644
--- a/Tests/test_imageshow.py
+++ b/Tests/test_imageshow.py
@@ -78,6 +78,10 @@ def test_commandviewer():
         basecmd = "rm -f {file}"
     viewer = ImageShow.CommandViewer()
     im = hopper()
+    with pytest.raises(TypeError):
+		viewer.get_command(viewer.save_image(im))
+    with pytest.raises(TypeError):
+		viewer.get_command(viewer.save_image(im), command=5)
     viewer.get_command(viewer.save_image(im), command=basecmd)