diff --git a/labscript_utils/qtwidgets/headerview_with_widgets.py b/labscript_utils/qtwidgets/headerview_with_widgets.py
index 89fdaef..a0e6672 100644
--- a/labscript_utils/qtwidgets/headerview_with_widgets.py
+++ b/labscript_utils/qtwidgets/headerview_with_widgets.py
@@ -122,7 +122,7 @@ def update_indents(self):
                 font = item.font()
                 fontmetrics = QtGui.QFontMetrics(font, self)
                 indent = ''
-                while fontmetrics.width(indent) < desired_indent:
+                while fontmetrics.horizontalAdvance(indent) < desired_indent:
                     indent += self.thinspace
                 self.indents[widget] = indent
         font = self.font()