diff --git a/proton b/proton
index 19313b9e7..ac3fefd4d 100755
--- a/proton
+++ b/proton
@@ -476,7 +476,7 @@ if "nod3d10" in config_opts:
     dlloverrides["dxgi"] = ""
 
 if "nod3d9" in config_opts:
-    dlloverrides["d3d9"] = ""
+    dlloverrides["d3d9"] = "builtin"
 
 s = ""
 for dll in dlloverrides: