diff --git a/.github/workflows/spack.yml b/.github/workflows/spack.yml
index 2c56128..9ed8bf6 100644
--- a/.github/workflows/spack.yml
+++ b/.github/workflows/spack.yml
@@ -95,7 +95,7 @@ jobs:
           export TARGET_TRIPLET="${arch}_${{ inputs.compiler }}"
           echo "TARGET_TRIPLET=${TARGET_TRIPLET}" >> "$GITHUB_ENV"
           cp spack.lock "spack_${TARGET_TRIPLET}.lock"
-          if [ "${{ inputs.default }}" == "true" ]; then
+          if [[ "${{ inputs.default }}" == "true" ]]; then
             # this will be become the default combination for this architecture
             cp spack.lock "spack_${arch}.lock"
           fi
@@ -126,11 +126,11 @@ jobs:
           GH_OCI_USER: "${{ github.actor }}"
           GH_OCI_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
         run: |
-          if [ "${{ inputs.image }}" != "" ]; then
+          if [[ "${{ inputs.image }}" != "" ]]; then
             export BASE_IMAGE="${{ inputs.image }}"
-          elif [ "${{ inputs.os }}" == "ubuntu-22.04" ]; then
+          elif [[ "${{ inputs.os }}" == "ubuntu-22.04" ]]; then
             export BASE_IMAGE="ubuntu:22.04"
-          elif [ "${{ inputs.os }}" == "ubuntu-24.04" ]; then
+          elif [[ "${{ inputs.os }}" == "ubuntu-24.04" ]]; then
             export BASE_IMAGE="ubuntu:24.04"
           else
             export BASE_IMAGE="ubuntu:24.04"