diff --git a/README.md b/README.md
index 0ffe574..daacbb9 100644
--- a/README.md
+++ b/README.md
@@ -143,6 +143,16 @@ Make sure you store the yml files shown below in your repository under `.github/
                 ${{ steps.srtool_build.outputs.wasm }}
                 ${{ matrix.chain }}-srtool-digest.json
 
+## Environmental variables
+```
+...
+uses: chevdor/srtool-actions@v*
+env:
+  BUILD_OPTS: "--features on-chain-release-build" # optional: will be passed to docker srtool run cmd
+with:
+...
+```
+
 ## Dev notes
 
 Due to a [bug in act](https://github.com/nektos/act/issues/655), the defaults defined in the action are not applied. That means **must** pass all the inputs while testing with `act`.
diff --git a/README_src.adoc b/README_src.adoc
index ea73f1b..7396aab 100644
--- a/README_src.adoc
+++ b/README_src.adoc
@@ -47,3 +47,16 @@ If your project uses standard values (such as your runtime package being named `
 include::examples/index.adoc[leveloffset=+1]
 
 include::doc/dev-notes.adoc[]
+
+== Environmental variables
+
+[source,bash]
+----
+    ...
+    uses: chevdor/srtool-actions@v*
+    env:
+        # optional: will be passed to docker srtool run cmd
+        BUILD_OPTS: "--features on-chain-release-build"
+    with:
+        ...
+----
diff --git a/action.yml b/action.yml
index ce93876..20cde61 100644
--- a/action.yml
+++ b/action.yml
@@ -115,6 +115,8 @@ runs:
         PACKAGE=${PACKAGE:-${{ inputs.chain }}'-runtime'}
         echo "PACKAGE=$PACKAGE" >> $GITHUB_ENV
 
+        echo "BUILD_OPTS=${{ env.BUILD_OPTS }}" >> $GITHUB_ENV
+
         echo ::endgroup
 
     - id: env_check
@@ -129,6 +131,7 @@ runs:
         echo ℹ️ package: ${{ env.PACKAGE }}
         echo ℹ️ workdir: ${{ env.WORKDIR }}
         echo ℹ️ runtime_dir: ${{ env.RUNTIME_DIR }}
+        echo ℹ️ build_opts: ${{ env.BUILD_OPTS }}
         echo ℹ️ .git folder: `ls -ald ${{ env.WORKDIR }}/.git`
         echo ℹ️ Cargo.toml: `ls -al ${{ env.WORKDIR }}/Cargo.toml`
 
@@ -167,7 +170,7 @@ runs:
       shell: bash
       run: |
         echo ::group::Srtool build of chain ${{ inputs.chain }}
-        CMD="docker run -i --rm -e PACKAGE=${{ env.PACKAGE }} -e RUNTIME_DIR=${{ env.RUNTIME_DIR }} -v ${{ env.WORKDIR }}:/build ${{ env.SRTOOL_IMAGE }} build --app --json -cM"
+        CMD="docker run -i --rm -e PACKAGE=${{ env.PACKAGE }} -e RUNTIME_DIR=${{ env.RUNTIME_DIR }} -e BUILD_OPTS -v ${{ env.WORKDIR }}:/build ${{ env.SRTOOL_IMAGE }} build --app --json -cM"
         echo ::debug::build::docker_run $CMD
 
         # here we keep streaming the progress and fetch the last line for the json result