diff --git a/scripts/Diffraction/isis_powder/polaris.py b/scripts/Diffraction/isis_powder/polaris.py
index 57eecad48a1fed92bd6dc22921187eede41600f6..533fd554ac65b92a2b9cedcb1152d32029476caf 100644
--- a/scripts/Diffraction/isis_powder/polaris.py
+++ b/scripts/Diffraction/isis_powder/polaris.py
@@ -49,7 +49,7 @@ class Polaris(AbstractInst):
         return vanadium_d
 
     def create_total_scattering_pdf(self, **kwargs):
-        if not 'q_lims' in kwargs:
+        if 'q_lims' not in kwargs:
             kwargs['q_lims'] = None
         self._inst_settings.update_attributes(kwargs=kwargs)
         # Generate pdf