diff --git a/.gitignore b/.gitignore
index 2371c8fc0ac0b..b23fb12b30d7b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -134,6 +134,7 @@
 **/vendor/bundle/ruby/*/gems/rspec-support-*/
 **/vendor/bundle/ruby/*/gems/rspec-wait-*/
 **/vendor/bundle/ruby/*/gems/rubocop-0*/
+**/vendor/bundle/ruby/*/gems/ruby-prof-*/
 **/vendor/bundle/ruby/*/gems/ruby-progressbar-*/
 **/vendor/bundle/ruby/*/gems/simplecov-*/
 **/vendor/bundle/ruby/*/gems/simplecov-cobertura-*/
diff --git a/Library/Homebrew/dev-cmd/prof.rb b/Library/Homebrew/dev-cmd/prof.rb
index 4666fa0d0626d..aba6de4749978 100644
--- a/Library/Homebrew/dev-cmd/prof.rb
+++ b/Library/Homebrew/dev-cmd/prof.rb
@@ -18,7 +18,7 @@ def prof_args
   def prof
     prof_args.parse
 
-    Homebrew.install_gem_setup_path! "ruby-prof"
+    Homebrew.install_gem_setup_path! "ruby-prof", version: "0.18.0"
     FileUtils.mkdir_p "prof"
     brew_rb = (HOMEBREW_LIBRARY_PATH/"brew.rb").resolved_path
     safe_system "ruby-prof", "--printer=multi", "--file=prof", brew_rb, "--", *ARGV