diff --git a/LungCTAnalyzer/LungCTAnalyzer.py b/LungCTAnalyzer/LungCTAnalyzer.py
index eff34c9..7a86985 100644
--- a/LungCTAnalyzer/LungCTAnalyzer.py
+++ b/LungCTAnalyzer/LungCTAnalyzer.py
@@ -1496,7 +1496,7 @@ def shrinkLungMasks(self, millimeters=1.):
         segmentEditorNode.SetSelectedSegmentID(self.leftLungMaskSegmentID)
         segmentEditorWidget.setActiveEffectByName("Margin")
         effect = segmentEditorWidget.activeEffect()
-        effect.setParameter("MarginSizeMm",str(millimeters * -1.)
+        effect.setParameter("MarginSizeMm",str(millimeters * -1.))
         effect.self().onApply()
 
         # Delete temporary segment editor