diff --git a/.github/workflows/test-windows.yml b/.github/workflows/test-windows.yml
index febabaec..4831eac1 100644
--- a/.github/workflows/test-windows.yml
+++ b/.github/workflows/test-windows.yml
@@ -14,6 +14,9 @@ jobs:
     runs-on: windows-latest
     env:
       PYTHONIOENCODING: "utf8"
+      # uv hardlinks by default, which cannot replace a .pyd that is still
+      # loaded by another process on the runner (os error 5). Copy instead.
+      UV_LINK_MODE: copy
 
     steps:
       - name: Check out code