diff --git a/docs/docker.md b/docs/docker.md
index 53c14f845..f8842be39 100644
--- a/docs/docker.md
+++ b/docs/docker.md
@@ -29,7 +29,7 @@ RUN curl -sL https://deb.nodesource.com/setup_8.x | bash
 RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
 
 RUN apt-get install -y nodejs
-RUN apt-get update && apt-get install yarn
+RUN apt-get update && apt-get install -y yarn
 
 # Rest of the commands....
 ```