diff --git a/Dockerfile b/Dockerfile
index 581f9a6..ac34853 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -12,6 +12,8 @@ ENV NOKOGIRI_USE_SYSTEM_LIBRARIES=1
 ENV EXTRA_PKGS=''
 
 RUN id
+RUN gem env
+RUN ls -hal /usr/lib/ruby/gems/2.7.0
 RUN gem install --no-user-install --no-document --source https://rubygems.org geminabox mini_portile2 gem-compiler
 
 COPY ./gem-compiler.sh /usr/local/bin/gem-compiler