diff --git a/templates/install_mastodon.sh.erb b/templates/install_mastodon.sh.erb
index 8fdf7de..5fee97d 100644
--- a/templates/install_mastodon.sh.erb
+++ b/templates/install_mastodon.sh.erb
@@ -6,7 +6,9 @@ if [ ! -e '<%= @mastodon_home %>/.mastodon_install' ]; then
     echo "Installing ruby..."
     export PATH="<%= @mastodon_home %>/.rbenv/bin:$PATH"
     eval "$(<%= @mastodon_home %>/.rbenv/bin/rbenv init -)"
-    sudo -u <%= @mastodon_user %> RUBY_CONFIGURE_OPTS=--with-jemalloc '<%= @mastodon_home %>/.rbenv/bin/rbenv' install '<%= @ruby_version %>'
+    if [ ! -e '<%= @mastodon_home %>/.rbenv/version/<%= @ruby_version %>/bin/ruby' ]; then
+        sudo -u <%= @mastodon_user %> RUBY_CONFIGURE_OPTS=--with-jemalloc '<%= @mastodon_home %>/.rbenv/bin/rbenv' install '<%= @ruby_version %>'
+    fi
     sudo -u <%= @mastodon_user %> '<%= @mastodon_home %>/.rbenv/bin/rbenv' global '<%= @ruby_version %>'
     sudo -u <%= @mastodon_user %> '<%= @mastodon_home %>/.rbenv/versions/<%= @ruby_version %>/bin/gem' install bundler --no-document
     echo "Configuring bundle..."