diff --git a/Library/Homebrew/deprecate_disable.rb b/Library/Homebrew/deprecate_disable.rb
index e6ed2ef2c8e078..05e85ec8edae2c 100644
--- a/Library/Homebrew/deprecate_disable.rb
+++ b/Library/Homebrew/deprecate_disable.rb
@@ -1,4 +1,4 @@
-# typed: true # rubocop:todo Sorbet/StrictSigil
+# typed: strict
 # frozen_string_literal: true
 
 # Helper module for handling `disable!` and `deprecate!`.
@@ -6,7 +6,7 @@
 module DeprecateDisable
   module_function
 
-  FORMULA_DEPRECATE_DISABLE_REASONS = {
+  FORMULA_DEPRECATE_DISABLE_REASONS = T.let({
     does_not_build:      "does not build",
     no_license:          "has no license",
     repo_archived:       "has an archived upstream repository",
@@ -19,27 +19,29 @@ module DeprecateDisable
                          "a different checksum than the current one. " \
                          "Upstream's repository might have been compromised. " \
                          "We can re-package this once upstream has confirmed that they retagged their release",
-  }.freeze
+  }.freeze, T::Hash[Symbol, String])
 
-  CASK_DEPRECATE_DISABLE_REASONS = {
+  CASK_DEPRECATE_DISABLE_REASONS = T.let({
     discontinued:             "is discontinued upstream",
     moved_to_mas:             "is now exclusively distributed on the Mac App Store",
     no_longer_available:      "is no longer available upstream",
     no_longer_meets_criteria: "no longer meets the criteria for acceptable casks",
     unmaintained:             "is not maintained upstream",
     unsigned:                 "is unsigned or does not meet signature requirements",
-  }.freeze
+  }.freeze, T::Hash[Symbol, String])
 
   # One year when << or >> to Date.today.
   REMOVE_DISABLED_TIME_WINDOW = 12
-  REMOVE_DISABLED_BEFORE = (Date.today << REMOVE_DISABLED_TIME_WINDOW).freeze
+  REMOVE_DISABLED_BEFORE = T.let((Date.today << REMOVE_DISABLED_TIME_WINDOW).freeze, Date)
 
+  sig { params(formula_or_cask: T.any(Formula, Cask::Cask)).returns(T.nilable(Symbol)) }
   def type(formula_or_cask)
     return :deprecated if formula_or_cask.deprecated?
 
     :disabled if formula_or_cask.disabled?
   end
 
+  sig { params(formula_or_cask: T.any(Formula, Cask::Cask)).returns(T.nilable(String)) }
   def message(formula_or_cask)
     return if type(formula_or_cask).blank?
 
@@ -92,9 +94,12 @@ def message(formula_or_cask)
     message
   end
 
+  sig { params(string: T.nilable(String), type: Symbol).returns(T.nilable(T.any(String, Symbol))) }
   def to_reason_string_or_symbol(string, type:)
-    if (type == :formula && FORMULA_DEPRECATE_DISABLE_REASONS.key?(string&.to_sym)) ||
-       (type == :cask && CASK_DEPRECATE_DISABLE_REASONS.key?(string&.to_sym))
+    return if string.nil?
+
+    if (type == :formula && FORMULA_DEPRECATE_DISABLE_REASONS.key?(string.to_sym)) ||
+       (type == :cask && CASK_DEPRECATE_DISABLE_REASONS.key?(string.to_sym))
       return string.to_sym
     end