diff --git a/MDANSE_GUI/Src/MDANSE_GUI/Widgets/ResolutionDialog.py b/MDANSE_GUI/Src/MDANSE_GUI/Widgets/ResolutionDialog.py
index 9dec368aa1..f27bb0e25d 100644
--- a/MDANSE_GUI/Src/MDANSE_GUI/Widgets/ResolutionDialog.py
+++ b/MDANSE_GUI/Src/MDANSE_GUI/Widgets/ResolutionDialog.py
@@ -245,7 +245,7 @@ def recalculate_peak(self):
         of points around the peak centre.
         """
         try:
-            fwhm = float(self._fwhm.text())
+            fwhm = abs(float(self._fwhm.text()))
         except:
             return
         try: