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If you're trying to get rid of mouse acceleration in OS X, use SmoothMouse!



Version 1.2.1 - 19/09/2009

Updated mousefix so it will compile/run on 10.6 (Intel-only, sorry)
binaries available at
- Allen "Chip" Parker -

Version 1.2 - 20/08/2006

Copyright (c) 2005 - Richard Bentley -

23/07/2005 - V 1.0 - Initial version
16/02/2006 : V 1.1 - Lance Burns suggested enabling the acceleration table (this was disabled
                     in V 1.0) and setting the values within it to {1, 1}, {2, 1}. This seems
                     to generate a more linear response. I have no idea why this works and
                     neither has Lance Burns (!) but there you go. Maybe if the mouse driver
                     wasn't so badly written then we could make sense of it :-)
20/08/2006 : V 1.2 - Aaron Johnson suggested a modification to the acceleration curve based
                     on similar data used in MS Windows XP. See the source code for further
                     details. He has suggested that it works best with an acceleration factor
                     of 2 (the source code has been modified to this value, but it may be
                     altered on the command line when executing mousefix). Many thanks to
                     Aaron Johnson for this suggestion.

This software is provided as-is and is used entirely at your own risk.

This software may be freely distributed, however no payment may be demanded or offered for it
(either monetary, in kind, through offers of any weird sex acts, or anything else).

MouseFix is a very simple command line program that will allow you to switch off or adjust the
terrible mouse control of Mac OS-X. Note that even with MouseFix, the mouse movement can still
be pretty ropey, so either I've not hit on the optimal values to use or the driver is just not
very good.

Copies of this software may be found at

As you are reading this, it is assumed that you have managed to unpack MouseFix from its archive

If you are building from source then you will first need to make sure you have the developer kit
installed. This is available on the standard OS-X DVD that comes with your machine. There is rather
a lot of it though so unless you intend doing some other development work or you find that you
absolutely must build from source, you may not want to bother, in which case get hold of the
pre-compiled version of MouseFix from

If you look at the top of the source file you will see the configuration parameters that you can
adjust. I have tried to comment them as best I can but I'm not familiar with OS-X's driver
architecture so apologies if I am wide of the mark. Anyway, the stuff is there if you want it.

To compile:
> cc mousefix.c -o mousefix /usr/lib/libIOKit.A.dylib

Optionally (to reduce the executable size - not that it matters)...
> strip mousefix

...or run the make script included with the source, thus:

> ./make

There isn't actually any 'installation' required as such. the 'mousefix' executable is self
contained and works as it is.

To run it from the command line, type the following:

This will fix the mouse settings with default values that may well be ok for you...
> ./mousefix

This will fix the mouse settings using an acceleration factor of 3.5...
> ./mousefix 3.5

This will print some help...
> ./mousefix h

Once you have found some settings that work for you then you will probably want to have them set
automatically at startup (they will be lost when you power off). To do this:

1/ Copy the 'mousefix' executable somewhere where it's not likely to be in the way, such as
   /Applications or maybe a local 'utilities' directory or suchlike.

   Note that you will have to be an admin user to copy mousefix to /Applications

Before diving in, I suggest you read both the following options and choose which one you want to
use :-)

2A/ METHOD #1 - The broken 'Mac' way (doesn't inspire confidence, does it?)...
   Open 'System Preferences'
   - Select 'Accounts' from the 'System' category
   - Select the appropriate account (you will need to be an admin user to select any account
     other than your own)
   - Select the 'Login Items' tab
   - Click on the '+' and find the MouseFix program and select 'Add'

   There are two problems with this method.
   * Firstly, you can't specify any parameters to mousefix when it starts (or at least if you can,
     I don't know how you do it). So, if you are not happy with the defaults that are defined in
     mousefix then you have a problem. The only solution is to modify the source code to match
     what you want and rebuild it
   * The second problem is that after starting, you are left with a console window open on the
     screen that you can't do anything with except close! Not a big problem, but annoying.
     I don't know how to stop this happening either.

2B/ METHOD #2 - The simple, common sense way...
   If you look in your home directory you may find a file called '.profile' (note the preceding
   '.' in the name - it is important!)

   If this file already exists then load it into an editor. If it doesn't then create it. A quick
   way of creating it is to open a command line and type:

   > touch .profile

   At the end of the '.profile' file, add the following:


   ...or if you want to specify a different acceleration factor (eg - 3.5), then...

   /Applications/mousefix 3.5

   There are no problems with this method (assuming you are using the default bash shell, and
   if you aren't using the default shell then you probably know what you're doing anyway and
   won't be reading this)

   ...and as you've probably surmised by now, this works without leaving a console on the
   screen at boot up, and there are no problems with specifying parameters to mousefix from
   within the .profile file (well, there wouldn't be, would there?)

Someone complained about not being able to uninstall MouseFix. Well, to 'uninstall' it, you :
1/ Stop executing it
2/ Delete the executable

Errr... that really is all there is to it. Honest!


Well, that's it!

--- END ---


mousefix for OS X from Richard Bentley with some tiny tweaks






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