diff --git a/.rubocop.yml b/.rubocop.yml
index 4bc466f9..a86d3184 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -39,6 +39,9 @@ Layout/CaseIndentation:
 Layout/FirstArrayElementIndentation:
   EnforcedStyle: consistent
 
+Layout/FirstHashElementIndentation:
+  EnforcedStyle: consistent
+
 Layout/EndAlignment:
   EnforcedStyleAlignWith: variable
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b16cddbc..ccc36c3f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Fixed
+
+- Using a hash as custom cache in `Pundit.authorize` now works as documented. (#838)
+
 ## 2.4.0 (2024-08-26)
 
 ## Changed
diff --git a/lib/pundit.rb b/lib/pundit.rb
index a7263b39..79c0d700 100644
--- a/lib/pundit.rb
+++ b/lib/pundit.rb
@@ -74,7 +74,8 @@ class << self
     # @see Pundit::Context#authorize
     def authorize(user, record, query, policy_class: nil, cache: nil)
       context = if cache
-        Context.new(user: user, policy_cache: cache)
+        policy_cache = CacheStore::LegacyStore.new(cache)
+        Context.new(user: user, policy_cache: policy_cache)
       else
         Context.new(user: user)
       end
diff --git a/spec/pundit_spec.rb b/spec/pundit_spec.rb
index 65d13b77..260b5a2e 100644
--- a/spec/pundit_spec.rb
+++ b/spec/pundit_spec.rb
@@ -125,6 +125,18 @@
         expect(Pundit.authorize(user, [:project, comment], :create?, policy_class: PublicationPolicy)).to be_truthy
       end
     end
+
+    context "when passed an explicit cache" do
+      it "uses the hash assignment interface on the cache" do
+        custom_cache = CustomCache.new
+
+        Pundit.authorize(user, post, :update?, cache: custom_cache)
+
+        expect(custom_cache.to_h).to match({
+          post => kind_of(PostPolicy)
+        })
+      end
+    end
   end
 
   describe ".policy_scope" do
diff --git a/spec/support/lib/custom_cache.rb b/spec/support/lib/custom_cache.rb
new file mode 100644
index 00000000..85d7ccb8
--- /dev/null
+++ b/spec/support/lib/custom_cache.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class CustomCache
+  def initialize
+    @store = {}
+  end
+
+  def to_h
+    @store
+  end
+
+  def [](key)
+    @store[key]
+  end
+
+  def []=(key, value)
+    @store[key] = value
+  end
+end