diff --git a/.github/workflows/firefox-metadata.yml b/.github/workflows/firefox-metadata.yml
index e4f12a22..212bc6fa 100644
--- a/.github/workflows/firefox-metadata.yml
+++ b/.github/workflows/firefox-metadata.yml
@@ -27,8 +27,15 @@ jobs:
         run: npm ci
 
       - name: Update Firefox metadata
-        run: npm run release:update-firefox-metadata -- --version "${{ inputs.version }}"
+        run: |
+          if [[ ! "$FIREFOX_METADATA_VERSION" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+            echo "Firefox version must use x.y.z semver format" >&2
+            exit 1
+          fi
+
+          npm run release:update-firefox-metadata -- --version "$FIREFOX_METADATA_VERSION"
         env:
+          FIREFOX_METADATA_VERSION: ${{ inputs.version }}
           FIREFOX_EXTENSION_ID: ${{ secrets.FIREFOX_EXTENSION_ID }}
           FIREFOX_JWT_ISSUER: ${{ secrets.FIREFOX_JWT_ISSUER }}
           FIREFOX_JWT_SECRET: ${{ secrets.FIREFOX_JWT_SECRET }}