diff --git a/README.md b/README.md
index 25acd107..e1919f4d 100644
--- a/README.md
+++ b/README.md
@@ -275,6 +275,7 @@ the Wine prefix. Removing the option will revert to the previous behavior.
 | <tt>forcelgadd</tt>   | <tt>PROTON_FORCE_LARGE_ADDRESS_AWARE</tt> | Force Wine to enable the LARGE_ADDRESS_AWARE flag for all executables. Enabled by default. |
 | <tt>noforcelgadd</tt> |                                | Disable forcelgadd. If both this and `forcelgadd` are set, enabled wins. |
 | <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>vkd3dfl12</tt>    |                                | Force the Direct3D 12 feature level to 12, regardless of driver support. |
 |                       | <tt>WINE_FULLSCREEN_INTEGER_SCALING</tt> | Enable integer scaling mode, to give sharp pixels when upscaling. |
 | <tt>cmdlineappend:</tt>|                               | Append the string after the colon as an argument to the game command. May be specified more than once. Escape commas and backslashes with a backslash. |
 | <tt>d9vk</tt>         | <tt>PROTON_USE_D9VK</tt>       | **Note: Obsoleted in Proton 5.0.** In older versions, use Vulkan-based DXVK instead of OpenGL-based wined3d for d3d9. |
diff --git a/proton b/proton
index f2a2ab14..14c83d27 100755
--- a/proton
+++ b/proton
@@ -523,6 +523,10 @@ class Session:
         if "forcelgadd" in self.compat_config:
             self.env["WINE_LARGE_ADDRESS_AWARE"] = "1"
 
+        if "vkd3dfl12" in self.compat_config:
+            if not "VKD3D_FEATURE_LEVEL" in self.env:
+                self.env["VKD3D_FEATURE_LEVEL"] = "12_0"
+
         if "SteamGameId" in self.env:
             if self.env["WINEDEBUG"] != "-all":
                 lfile_path = os.environ["HOME"] + "/steam-" + os.environ["SteamGameId"] + ".log"