-let regexp dust = "%%" [^ '\n']* '\n'
-let regexp comment_char = [^ "*)" ]
-let regexp note = "(*" comment_char* "*)"
-let regexp commentbegin = "(**"
-let regexp commentend = "**)"
+
+let regexp comment_char = [^'*'] | '*'[^')']
+let regexp note = "(*" ([^'*'] | "**") comment_char* "*)"
+
+let regexp commentbegin = "(**" blank
+let regexp commentend = "*)"
+