diff --git a/README.md b/README.md
index 939610d2..7cbdf66f 100644
--- a/README.md
+++ b/README.md
@@ -276,5 +276,6 @@ the Wine prefix. Removing the option will revert to the previous behavior.
 | <tt>nofsync</tt>      | <tt>PROTON_NO_FSYNC</tt>       | Do not use futex-based in-process synchronization primitives. (Automatically disabled on systems with no `FUTEX_WAIT_MULTIPLE` support.) |
 | <tt>forcelgadd</tt>   | <tt>PROTON_FORCE_LARGE_ADDRESS_AWARE</tt> | Force Wine to enable the LARGE_ADDRESS_AWARE flag for all executables. |
 | <tt>oldglstr</tt>     | <tt>PROTON_OLD_GL_STRING</tt>  | Set some driver overrides to limit the length of the GL extension string, for old games that crash on very long extension strings. |
+|                       | <tt>WINE_FULLSCREEN_INTEGER_SCALING</tt> | Enable integer scaling mode, to give sharp pixels when upscaling. |
 
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