diff --git a/gammapy_tools/make_background/background_models.py b/gammapy_tools/make_background/background_models.py
index 57b72f9..1e6f8f2 100644
--- a/gammapy_tools/make_background/background_models.py
+++ b/gammapy_tools/make_background/background_models.py
@@ -389,7 +389,7 @@ def background_rate(self):
             rate = smooth(rate, sigma=self.smooth_sigma)
         return rate
 
-def smooth(bkg, method='poly'):
+def smooth(bkg, method='poly',sigma=1):
     """Smooths background rates from BackgroundModelEstimator.background_rate (bkg input)