diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 12098172..f486fa86 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -214,7 +214,7 @@ jobs:
           [[ "${MATRIX_IMAGE}" = *'macos'* ]] && export CFLAGS='-arch arm64'
           if [[ "${MATRIX_IMAGE}" = *'windows'* ]]; then
             export TEST_CMAKE_GENERATOR='MSYS Makefiles'
-            export TEST_CMAKE_FLAGS='-DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc -DOPENSSL_ROOT_DIR=C:/msys64/ucrt64'
+            export TEST_CMAKE_FLAGS='-DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc -DOPENSSL_ROOT_DIR=/ucrt64'
           fi
           ./tests/cmake/test.sh add_subdirectory -DCRYPTO_BACKEND=OpenSSL
 
@@ -224,7 +224,7 @@ jobs:
           [[ "${MATRIX_IMAGE}" = *'macos'* ]] && export CFLAGS='-arch arm64'
           if [[ "${MATRIX_IMAGE}" = *'windows'* ]]; then
             export TEST_CMAKE_GENERATOR='MSYS Makefiles'
-            export TEST_CMAKE_FLAGS='-DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc -DOPENSSL_ROOT_DIR=C:/msys64/ucrt64'
+            export TEST_CMAKE_FLAGS='-DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc -DOPENSSL_ROOT_DIR=/ucrt64'
           fi
           ./tests/cmake/test.sh find_package -DCRYPTO_BACKEND=OpenSSL