diff --git a/pyqtgraph/tests/image_testing.py b/pyqtgraph/tests/image_testing.py
index 1245bb02..1fcfeb53 100644
--- a/pyqtgraph/tests/image_testing.py
+++ b/pyqtgraph/tests/image_testing.py
@@ -603,7 +603,7 @@ def runSubprocess(command, return_code=False, **kwargs):
     if p.returncode != 0:
         print(output)
         err_fun = sp.CalledProcessError.__init__
-        if 'output' in inspect.getargspec(err_fun).args:
+        if 'output' in inspect.getfullargspec(err_fun).args:
             raise sp.CalledProcessError(p.returncode, command, output)
         else:
             raise sp.CalledProcessError(p.returncode, command)