diff --git a/artiq-fast/conda-windows/binutils.nix b/artiq-fast/conda-windows/binutils.nix
index 0e80ba1..e425f51 100644
--- a/artiq-fast/conda-windows/binutils.nix
+++ b/artiq-fast/conda-windows/binutils.nix
@@ -29,7 +29,7 @@ let
       EOF
 
       cat > bld.bat << EOF
-      set MSYS=C:\\MSYS64
+      set MSYS=C:\MSYS64
       set TOOLPREF=mingw-w64-x86_64-
       set TRIPLE=x86_64-pc-mingw64
       set PATH=%MSYS%\usr\bin;%MSYS%\mingw64\bin;%PATH%