diff --git a/Rakefile b/Rakefile
index af045d4..6574d3a 100644
--- a/Rakefile
+++ b/Rakefile
@@ -27,11 +27,12 @@ end
 
 desc "Type check lib against the RBS comments in it"
 task :steep do
-  # RBS reads source with the default external encoding, so under a C
-  # locale every em dash in a comment is an invalid byte rather than a
-  # character and the check dies parsing them. The same footgun the
-  # ASCII-only rule in config.ru exists for.
-  sh({"RUBYOPT" => "#{ENV.fetch('RUBYOPT', '')} -EUTF-8"}, "steep", "check")
+  # RBS reads source with the default external encoding, so this needs a
+  # UTF-8 locale: under a C one every em dash in a comment is an invalid
+  # byte rather than a character and the check dies parsing them. LANG is
+  # set in .ramekin/config.kdl for agents and by the login environment
+  # otherwise. The same footgun the ASCII-only rule in config.ru exists for.
+  sh "steep", "check"
 end
 
 desc "Render the macOS configuration profile (carddav.mobileconfig)"
@@ -74,4 +75,4 @@ namespace :profile do
   end
 end
 
-task default: :test
+task default: %i[ steep test ]