diff --git a/EDMarketConnector.py b/EDMarketConnector.py
index 7fa77c99..56881f91 100755
--- a/EDMarketConnector.py
+++ b/EDMarketConnector.py
@@ -156,7 +156,7 @@ class AppWindow:
         if platform=='darwin':
             # Can't handle (de)iconify if topmost is set, so suppress iconify button
             # http://wiki.tcl.tk/13428 and p15 of https://developer.apple.com/legacy/library/documentation/Carbon/Conceptual/HandlingWindowsControls/windowscontrols.pdf
-            root.call('tk::unsupported::MacWindowStyle', 'style', root, 'document', 'closeBox horizontalZoom resizable')
+            root.call('tk::unsupported::MacWindowStyle', 'style', root, 'document', 'closeBox resizable')
 
             # https://www.tcl.tk/man/tcl/TkCmd/menu.htm
             self.system_menu = tk.Menu(self.menubar, name='apple')
@@ -187,6 +187,7 @@ class AppWindow:
             self.w.createcommand("::tk::mac::ShowPreferences", lambda:prefs.PreferencesDialog(self.w, self.postprefs))
             self.w.createcommand("::tk::mac::ReopenApplication", self.w.deiconify)	# click on app in dock = restore
             self.w.protocol("WM_DELETE_WINDOW", self.w.withdraw)	# close button shouldn't quit app
+            self.w.resizable(tk.FALSE, tk.FALSE)	# Can't be only resizable on one axis
         else:
             self.file_menu = self.view_menu = tk.Menu(self.menubar, tearoff=tk.FALSE)
             self.file_menu.add_command(command=lambda:stats.StatsDialog(self))
@@ -248,6 +249,7 @@ class AppWindow:
             tk.Label(self.blank_menubar).grid()
             tk.Label(self.blank_menubar).grid()
             theme.register_alternate((self.menubar, self.theme_menubar, self.blank_menubar), {'row':0, 'columnspan':2, 'sticky':tk.NSEW})
+            self.w.resizable(tk.TRUE, tk.FALSE)
 
         # update geometry
         if config.get('geometry'):
@@ -267,7 +269,6 @@ class AppWindow:
                 else:
                     self.w.geometry(config.get('geometry'))
         self.w.attributes('-topmost', config.getint('always_ontop') and 1 or 0)
-        self.w.resizable(tk.TRUE, tk.FALSE)
 
         theme.register(frame)
         theme.apply(self.w)
@@ -310,7 +311,7 @@ class AppWindow:
             tkMessageBox.showerror(applongname,
                                    _('This app requires accurate timestamps.') + '\n' +	# Error message shown if system time is wrong
                                    (TZ_THRESHOLD < drift < CLOCK_THRESHOLD and
-                                    _("Check your system's Time Zone setting.") or		# Error message shown if system time is wrong
+                                    _("Check your system's Time Zone setting.") or	# Error message shown if system time is wrong
                                     _("Check your system's Date and Time settings.")),	# Error message shown if system time is wrong
                                    parent = self.w)
             self.w.destroy()
diff --git a/theme.py b/theme.py
index 05ca660c..b5b1c8a1 100644
--- a/theme.py
+++ b/theme.py
@@ -161,40 +161,36 @@ class _Theme:
             self.active = theme
 
         if platform == 'darwin':
-            from AppKit import NSApplication, NSAppearance, NSColor
+            from AppKit import NSApplication, NSAppearance, NSMiniaturizableWindowMask, NSResizableWindowMask
             root.update_idletasks()	# need main window to be created
             appearance = NSAppearance.appearanceNamed_(theme and
                                                        'NSAppearanceNameVibrantDark' or
                                                        'NSAppearanceNameAqua')
             for window in NSApplication.sharedApplication().windows():
+                window.setStyleMask_(window.styleMask() & ~(NSMiniaturizableWindowMask | NSResizableWindowMask))	# disable zoom
                 window.setAppearance_(appearance)
 
-            if not self.minwidth:
-                self.minwidth = root.winfo_width()	# Minimum width = width on first creation
-                # resizable(0,0) doesn't do anything on OSX
-                root.minsize(self.minwidth, root.winfo_height())
-                root.maxsize(-1, root.winfo_height())
-
         elif platform == 'win32':
-            # tk8.5.9/win/tkWinWm.c:342
             import ctypes
+            GWL_STYLE = -16
+            WS_MAXIMIZEBOX   = 0x00010000
+            # tk8.5.9/win/tkWinWm.c:342
             GWL_EXSTYLE = -20
             WS_EX_APPWINDOW  = 0x00040000
             WS_EX_LAYERED    = 0x00080000
+            GetWindowLongW = ctypes.windll.user32.GetWindowLongW
+            SetWindowLongW = ctypes.windll.user32.SetWindowLongW
 
             root.overrideredirect(theme and 1 or 0)
             root.attributes("-transparentcolor", theme > 1 and 'grey4' or '')
             root.withdraw()
             root.update_idletasks()	# Size and windows styles get recalculated here
             hwnd = ctypes.windll.user32.GetParent(root.winfo_id())
-            ctypes.windll.user32.SetWindowLongW(hwnd, GWL_EXSTYLE, theme > 1 and WS_EX_APPWINDOW|WS_EX_LAYERED or WS_EX_APPWINDOW)	# Add to taskbar
+            SetWindowLongW(hwnd, GWL_STYLE, GetWindowLongW(hwnd, GWL_STYLE) & ~WS_MAXIMIZEBOX)	# disable maximize
+            SetWindowLongW(hwnd, GWL_EXSTYLE, theme > 1 and WS_EX_APPWINDOW|WS_EX_LAYERED or WS_EX_APPWINDOW)	# Add to taskbar
             root.deiconify()
             root.wait_visibility()	# need main window to be displayed before returning
 
-            if not self.minwidth:
-                self.minwidth = root.winfo_width()	# Minimum width = width on first creation
-                root.minsize(self.minwidth, -1)
-
         else:
             root.overrideredirect(theme and 1 or 0)
             root.withdraw()
@@ -202,9 +198,9 @@ class _Theme:
             root.deiconify()
             root.wait_visibility()	# need main window to be displayed before returning
 
-            if not self.minwidth:
-                self.minwidth = root.winfo_width()	# Minimum width = width on first creation
-                root.minsize(self.minwidth, -1)
+        if not self.minwidth:
+            self.minwidth = root.winfo_width()	# Minimum width = width on first creation
+            root.minsize(self.minwidth, -1)
 
 # singleton
 theme = _Theme()