diff --git a/EDMarketConnector.py b/EDMarketConnector.py
index 765fa62f..f2f8fbb4 100755
--- a/EDMarketConnector.py
+++ b/EDMarketConnector.py
@@ -1062,13 +1062,20 @@ Locale LC_TIME: {locale.getlocale(locale.LC_TIME)}'''
     Translations.install(config.get('language') or None)  # Can generate errors so wait til log set up
 
     root = tk.Tk(className=appname.lower())
+
+    # UI Scaling
+    """
+    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 = 0
+        ui_scale = 100
         config.set('ui_scale', ui_scale)
     theme.default_ui_scale = root.tk.call('tk', 'scaling')
-    if ui_scale != 0:
-        root.tk.call('tk', 'scaling', float(ui_scale) / 100.0)
+    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)
 
     def messagebox_not_py3():
diff --git a/L10n/en.template b/L10n/en.template
index 1e5b6cb0..a8ca6dc6 100644
--- a/L10n/en.template
+++ b/L10n/en.template
@@ -529,8 +529,8 @@
 /* Label for 'UI Scaling' option [prefs.py] */
 "UI Scale Percentage" = "UI Scale Percentage";
 
-/* Text describing that value '0' means 'default', and changes require a restart [prefs.py] */
-"0 means Default{CR}Restart Required for{CR}changes to take effect!" = "0 means Default{CR}Restart Required for{CR}changes to take effect!";
+/* Text describing that value '100' means 'default', and changes require a restart [prefs.py] */
+"100 means Default{CR}Restart Required for{CR}changes to take effect!" = "100 means Default{CR}Restart Required for{CR}changes to take effect!";
 
 /* Label for user configured level of logging [prefs.py] */
 "Log Level" = "Log Level";
diff --git a/prefs.py b/prefs.py
index 7643a8f6..6b2e824c 100644
--- a/prefs.py
+++ b/prefs.py
@@ -339,6 +339,13 @@ class PreferencesDialog(tk.Toplevel):
         self.theme_button_1.grid(row=21, column=1, padx=PADX, pady=PADY, sticky=tk.NSEW)
 
         # UI Scaling
+        """
+        The provided UI Scale setting is a percentage value relative to the
+        tk-scaling setting on startup.
+
+        So, if at startup we find tk-scaling is 1.33 and have a user setting
+        of 200 we'll end up setting 2.66 as the tk-scaling value.
+        """
         ttk.Separator(themeframe, orient=tk.HORIZONTAL).grid(columnspan=4, padx=PADX, pady=PADY*4, sticky=tk.EW)
         nb.Label(themeframe, text=_('UI Scale Percentage')).grid(row=23, padx=PADX, pady=2*PADY, sticky=tk.W)
         self.ui_scale = tk.IntVar()
@@ -347,7 +354,7 @@ class PreferencesDialog(tk.Toplevel):
             themeframe,
             variable=self.ui_scale,
             orient=tk.HORIZONTAL,
-            length=300,
+            length=300 * (float(theme.startup_ui_scale) / 100.0 * theme.default_ui_scale),
             from_=0,
             to=400,
             tickinterval=50,
@@ -356,7 +363,7 @@ class PreferencesDialog(tk.Toplevel):
         self.uiscale_bar.grid(row=23, column=1, sticky=tk.W)
         self.ui_scaling_defaultis = nb.Label(
             themeframe,
-            text=_('0 means Default{CR}Restart Required for{CR}changes to take effect!')
+            text=_('100 means Default{CR}Restart Required for{CR}changes to take effect!')
         ).grid(row=23, column=3, padx=PADX, pady=2*PADY, sticky=tk.E)
 
         # Always on top
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.