This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Windows FontSubtitutes rules not being followed on Firefox 109.0b7

  • 2 iimpendulo
  • 0 inale ngxaki
  • 1 view
  • Impendulo yokugqibela ngu Kotep

more options

I use the Windows registry FontSubstitutes (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes) to replace system fonts like Segoe UI with other fonts. It takes a lot of work to get Windows itself to respect these options, to the extent that I have to make it believe Segoe UI isn't present by modifying a different registry location (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts).

However, Firefox does not respect the FontSubstitutes settings. Based on a previous post here, this is something it did prior to Firefox 89, but has stopped doing.

An ideal solution would be a way for Firefox to correctly read my FontSubstitutes settings. An acceptable workaround would be a way to provide Segoe UI for Firefox to use while still preventing its use in other applications. (I know that, for instance, Adobe Photoshop allows users to install fonts to Photoshop itself, bypassing the system fonts folder entirely.)

I use the Windows registry FontSubstitutes (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes) to replace system fonts like Segoe UI with other fonts. It takes a lot of work to get Windows itself to respect these options, to the extent that I have to make it believe Segoe UI isn't present by modifying a different registry location (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts). However, Firefox does not respect the FontSubstitutes settings. Based on a previous post here, this is something it did prior to Firefox 89, but has stopped doing. An ideal solution would be a way for Firefox to correctly read my FontSubstitutes settings. An acceptable workaround would be a way to provide Segoe UI for Firefox to use while still preventing its use in other applications. (I know that, for instance, Adobe Photoshop allows users to install fonts to Photoshop itself, bypassing the system fonts folder entirely.)

Isisombulu esikhethiweyo

Could you try the workaround from back in the Firefox 89 days and let us know whether it still works:

https://support.mozilla.org/questions/1343838

Funda le mpendulo kwimeko leyo 👍 1

All Replies (2)

more options

Isisombululo esiKhethiweyo

Could you try the workaround from back in the Firefox 89 days and let us know whether it still works:

https://support.mozilla.org/questions/1343838

more options

Thanks, setting gfx.windows-font-substitutes.always to true still works.