diff --git a/EDMarketConnector.py b/EDMarketConnector.py
index b6e348a7..f2f8fbb4 100755
--- a/EDMarketConnector.py
+++ b/EDMarketConnector.py
@@ -1068,11 +1068,13 @@ Locale LC_TIME: {locale.getlocale(locale.LC_TIME)}'''
     We scale the UI relative to what we find tk-scaling is on startup.
     """
     ui_scale = config.getint('ui_scale')
+    # NB: This *also* catches a literal 0 value to re-set to the default 100
     if not ui_scale:
         ui_scale = 100
         config.set('ui_scale', ui_scale)
     theme.default_ui_scale = root.tk.call('tk', 'scaling')
     logger.debug(f'Default tk scaling = {theme.default_ui_scale}')
+    theme.startup_ui_scale = ui_scale
     root.tk.call('tk', 'scaling', theme.default_ui_scale * float(ui_scale) / 100.0)
     app = AppWindow(root)
 
diff --git a/prefs.py b/prefs.py
index 40cf8a93..6b2e824c 100644
--- a/prefs.py
+++ b/prefs.py
@@ -354,8 +354,8 @@ class PreferencesDialog(tk.Toplevel):
             themeframe,
             variable=self.ui_scale,
             orient=tk.HORIZONTAL,
-            length=300 * (float(config.getint('ui_scale')) / 100.0 * theme.default_ui_scale),
-            from_=10,
+            length=300 * (float(theme.startup_ui_scale) / 100.0 * theme.default_ui_scale),
+            from_=0,
             to=400,
             tickinterval=50,
             resolution=10,
diff --git a/theme.py b/theme.py
index f1a97721..d56b7798 100644
--- a/theme.py
+++ b/theme.py
@@ -116,6 +116,7 @@ class _Theme(object):
         self.defaults = {}
         self.current = {}
         self.default_ui_scale = None  # None == not yet known
+        self.startup_ui_scale = None
 
     def register(self, widget):
         # Note widget and children for later application of a theme. Note if the widget has explicit fg or bg attributes.