[users@httpd] mod_ext_filter - cannot escape forward slash

["Jack Saunders" <jack.g.saunders@xxxxxxxxx>]

Using sed as an output filter to replace some text.  I can escape periods but not forward slashes.  It throws the following error.  

ExtFilterInType text/html ExtFilterOuttype (unchanged)
/usr/bin/sed: -e _expression_ #1, char 14: unknown option to `s'

Apache config
ExtFilterDefine fix mode=output intype=text/html cmd="/usr/bin/sed s/test1/app1\//g"

<Location /app1>
SetOutputFilter fix
ExtFilterOptions LogStderr DebugLevel=3
</Location>

Filter will work fine if the "\/" is removed from above.

Any ideas?
Server version: Apache/2.0.59