diff --git a/Dockerfile.env b/Dockerfile.env
index 40dfd683..eee307da 100644
--- a/Dockerfile.env
+++ b/Dockerfile.env
@@ -33,11 +33,12 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --default-toolchain none -y \
     && rustup toolchain install $RUST_VERSION --allow-downgrade --profile minimal --component rustfmt clippy \
-    && curl -sL https://deb.nodesource.com/setup_lts.x | bash - && apt-get install -y nodejs && npm i -g solc wasm-pack \
+    && curl -sL https://deb.nodesource.com/setup_14.x | bash - && apt-get install -y nodejs && npm i -g solc \
+    && curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh \
     && curl -sL https://raw.githubusercontent.com/Sarcasm/run-clang-format/master/run-clang-format.py > /opt/run-clang-format.py \
     && chmod +x /opt/run-clang-format.py \
     && ln -s /opt/run-clang-format.py /usr/bin \
-    && rustup --version; cargo --version; rustc --version; echo nodejs $(node -v);
+    && rustup --version; cargo --version; rustc --version; wasm-pack --version; echo nodejs $(node -v);
 
 RUN cd /opt && curl -LO https://github.com/mozilla/geckodriver/releases/download/v0.28.0/geckodriver-v0.28.0-linux64.tar.gz \
     && tar -xzf geckodriver-v0.28.0-linux64.tar.gz geckodriver \
diff --git a/zokrates_js/publish.sh b/zokrates_js/publish.sh
index 681dcd1a..f625a0c0 100755
--- a/zokrates_js/publish.sh
+++ b/zokrates_js/publish.sh
@@ -24,6 +24,12 @@ if [ $NPM_VERSION = $PACKAGE_VERSION ]; then
     exit 0
 fi
 
+# make sure the pkg folder is present
+if [ ! -d "pkg" ]; then
+  echo "pkg folder is missing"
+  exit 1
+fi
+
 # publish
 npm set //registry.npmjs.org/:_authToken=${NPM_TOKEN}
 npm publish
\ No newline at end of file