diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index d739e58135b..ae77a6d88c8 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -97,6 +97,7 @@ jobs:
           # can't figure out how to pass the number of cores here :/
           echo exec -- make "-j=$env:NUMBER_OF_PROCESSORS"
           echo "exec -- make -j=$env:NUMBER_OF_PROCESSORS"
+          (& opam env) -split '\r?\n' | ForEach-Object { Invoke-Expression $_ }
           opam exec -- make -s -f Makefile.win -j "$env:NUMBER_OF_PROCESSORS" haxe
           opam exec -- make -s -f Makefile.win haxelib
           opam exec -- make -f Makefile.win echo_package_files package_bin package_installer_win package_choco
diff --git a/extra/github-actions/build-windows.yml b/extra/github-actions/build-windows.yml
index e54f81b0db8..5ec0ac83507 100644
--- a/extra/github-actions/build-windows.yml
+++ b/extra/github-actions/build-windows.yml
@@ -23,6 +23,7 @@
     # can't figure out how to pass the number of cores here :/
     echo exec -- make "-j=$env:NUMBER_OF_PROCESSORS"
     echo "exec -- make -j=$env:NUMBER_OF_PROCESSORS"
+    (& opam env) -split '\r?\n' | ForEach-Object { Invoke-Expression $_ }
     opam exec -- make -s -f Makefile.win -j "$env:NUMBER_OF_PROCESSORS" haxe
     opam exec -- make -s -f Makefile.win haxelib
     opam exec -- make -f Makefile.win echo_package_files package_bin package_installer_win package_choco