diff --git a/Library/Homebrew/requirements/language_module_dependency.rb b/Library/Homebrew/requirements/language_module_dependency.rb
index 90432562d1..2843c5c6cc 100644
--- a/Library/Homebrew/requirements/language_module_dependency.rb
+++ b/Library/Homebrew/requirements/language_module_dependency.rb
@@ -25,7 +25,7 @@ class LanguageModuleDependency < Requirement
       when :jruby then %W{/usr/bin/env jruby -rubygems -e require\ '#{@import_name}'}
       when :lua then %W{/usr/bin/env luarocks show #{@import_name}}
       when :node then %W{/usr/bin/env node -e require('#{@import_name}');}
-      when :ocaml then %W{/usr/bin/env opam list #{@import_name}}
+      when :ocaml then %W{/usr/bin/env opam list --installed #{@import_name}}
       when :perl then %W{/usr/bin/env perl -e use\ #{@import_name}}
       when :python then %W{/usr/bin/env python -c import\ #{@import_name}}
       when :python3 then %W{/usr/bin/env python3 -c import\ #{@import_name}}