diff --git a/images/etherpad/Dockerfile b/images/etherpad/Dockerfile
index 2a15e40..7c5e424 100644
--- a/images/etherpad/Dockerfile
+++ b/images/etherpad/Dockerfile
@@ -34,7 +34,7 @@ RUN install_packages ca-certificates curl
 RUN curl -sSL -o - https://raw.githubusercontent.com/nvm-sh/nvm/v0.38.0/install.sh | bash || true
 RUN mkdir -p /.npm \
 	&& chmod +x $HOME/.nvm/nvm.sh \
-    && source $HOME/.nvm/nvm.sh \
+    && . $HOME/.nvm/nvm.sh \
 	&& nvm install $NODE_VERSION \
 	&& nvm alias default $NODE_VERSION \
 	&& nvm use default \