--- a/QScintilla/Shell.py	Sat Nov 16 18:02:43 2013 +0100
+++ b/QScintilla/Shell.py	Sat Nov 16 18:37:27 2013 +0100
@@ -426,8 +426,9 @@
         @param on flag to indicate usage of a monospace font (boolean)
         """
         if on:
-            f = Preferences.getShell("MonospacedFont")
-            self.monospacedStyles(f)
+            if not self.lexer_:
+                f = Preferences.getShell("MonospacedFont")
+                self.monospacedStyles(f)
         else:
             if not self.lexer_:
                 self.clearStyles()