diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index 0d27bd2..70d21f5 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -51,15 +51,14 @@ jobs:
         
         # Replace variables in manifests and apply
         for manifest in k8s/*.yaml; do
-          envsubst < "$manifest" | kubectl apply -f -
+          sed -e "s/\${APP_NAME}/${{ env.APP_NAME }}/g" \
+              -e "s/\${NAMESPACE}/${{ env.NAMESPACE }}/g" \
+              -e "s/\${REGISTRY}/${{ env.REGISTRY }}/g" \
+              -e "s/\${IMAGE_NAME}/${{ env.IMAGE_NAME }}/g" \
+              -e "s/\${IMAGE_TAG}/${{ inputs.image_tag }}/g" \
+              -e "s/\${HOST}/${{ env.HOST }}/g" \
+              "$manifest" | kubectl apply -f -
         done
-      env:
-        APP_NAME: ${{ env.APP_NAME }}
-        NAMESPACE: ${{ env.NAMESPACE }}
-        REGISTRY: ${{ env.REGISTRY }}
-        IMAGE_NAME: ${{ env.IMAGE_NAME }}
-        IMAGE_TAG: ${{ inputs.image_tag }}
-        HOST: ${{ env.HOST }}
         
     - name: Verify deployment
       run: |