diff --git a/Library/Homebrew/env_config.rb b/Library/Homebrew/env_config.rb
index 35b56c45ee..b05296e6eb 100644
--- a/Library/Homebrew/env_config.rb
+++ b/Library/Homebrew/env_config.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 module Homebrew
@@ -8,7 +8,7 @@ module Homebrew
   module EnvConfig
     module_function
 
-    ENVS = {
+    ENVS = T.let({
       HOMEBREW_ALLOWED_TAPS:                     {
         description: "A space-separated list of taps. Homebrew will refuse to install a " \
                      "formula unless it and all of its dependencies are in an official tap " \
@@ -477,7 +477,7 @@ module Homebrew
         description: "A comma-separated list of hostnames and domain names excluded " \
                      "from proxying by `curl`(1), `git`(1) and `svn`(1) when downloading through Homebrew.",
       },
-    }.freeze
+    }.freeze, T::Hash[Symbol, T.untyped])
 
     sig { params(env: Symbol, hash: T::Hash[Symbol, T.untyped]).returns(String) }
     def env_method_name(env, hash)
@@ -488,10 +488,10 @@ module Homebrew
       method_name
     end
 
-    CUSTOM_IMPLEMENTATIONS = Set.new([
+    CUSTOM_IMPLEMENTATIONS = T.let(Set.new([
       :HOMEBREW_MAKE_JOBS,
       :HOMEBREW_CASK_OPTS,
-    ]).freeze
+    ]).freeze, T::Set[Symbol])
 
     ENVS.each do |env, hash|
       # Needs a custom implementation.