diff --git a/CHANGELOG.md b/CHANGELOG.md
index b710059..e8b82af 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,9 @@
 ### Unreleased
 * Add tests with Rails 7.2 and 8.0
-* Add tests with Ruby 3.4
+* Add tests with Ruby 3.4 and 4.0
 * Drop support for Ruby < 3.2
+* Curly::Presenter#dependencies now return an Array instead of a SortedSet. Entries in this array will still be sorted.
+* Drops dependency on sorted_set 
 
 ### Curly 3.4.0 (July 2, 2024)
 * Drop upper limit on Rails, test with Rails main.
diff --git a/curly-templates.gemspec b/curly-templates.gemspec
index f4cabd2..11f653a 100644
--- a/curly-templates.gemspec
+++ b/curly-templates.gemspec
@@ -19,7 +19,6 @@ Gem::Specification.new do |s|
   s.required_ruby_version = ">= 3.2"
 
   s.add_dependency("actionpack", ">= 6.1")
-  s.add_dependency("sorted_set")
 
   s.add_development_dependency("rake")
   s.add_development_dependency("rspec", ">= 3")
diff --git a/gemfiles/rails6.1.gemfile.lock b/gemfiles/rails6.1.gemfile.lock
index 383313a..db67768 100644
--- a/gemfiles/rails6.1.gemfile.lock
+++ b/gemfiles/rails6.1.gemfile.lock
@@ -12,7 +12,6 @@ PATH
   specs:
     curly-templates (3.4.0)
       actionpack (>= 6.1)
-      sorted_set
 
 GEM
   remote: https://rubygems.org/
@@ -147,7 +146,6 @@ GEM
       rake (>= 12.2)
       thor (~> 1.0)
     rake (13.1.0)
-    rbtree (0.4.6)
     redcarpet (3.6.0)
     rspec (3.12.0)
       rspec-core (~> 3.12.0)
@@ -170,10 +168,6 @@ GEM
       rspec-mocks (~> 3.12)
       rspec-support (~> 3.12)
     rspec-support (3.12.1)
-    set (1.0.3)
-    sorted_set (1.0.3)
-      rbtree
-      set (~> 1.0)
     sprockets (4.2.1)
       concurrent-ruby (~> 1.0)
       rack (>= 2.2.4, < 4)
diff --git a/gemfiles/rails7.0.gemfile.lock b/gemfiles/rails7.0.gemfile.lock
index 0af902e..7c4629e 100644
--- a/gemfiles/rails7.0.gemfile.lock
+++ b/gemfiles/rails7.0.gemfile.lock
@@ -12,7 +12,6 @@ PATH
   specs:
     curly-templates (3.4.0)
       actionpack (>= 6.1)
-      sorted_set
 
 GEM
   remote: https://rubygems.org/
@@ -153,7 +152,6 @@ GEM
       thor (~> 1.0)
       zeitwerk (~> 2.5)
     rake (13.1.0)
-    rbtree (0.4.6)
     redcarpet (3.6.0)
     rspec (3.12.0)
       rspec-core (~> 3.12.0)
@@ -176,10 +174,6 @@ GEM
       rspec-mocks (~> 3.12)
       rspec-support (~> 3.12)
     rspec-support (3.12.1)
-    set (1.0.3)
-    sorted_set (1.0.3)
-      rbtree
-      set (~> 1.0)
     stackprof (0.2.25)
     thor (1.3.0)
     timeout (0.4.1)
diff --git a/gemfiles/rails7.1.gemfile.lock b/gemfiles/rails7.1.gemfile.lock
index cb7380e..660f4c1 100644
--- a/gemfiles/rails7.1.gemfile.lock
+++ b/gemfiles/rails7.1.gemfile.lock
@@ -12,7 +12,6 @@ PATH
   specs:
     curly-templates (3.4.0)
       actionpack (>= 6.1)
-      sorted_set
 
 GEM
   remote: https://rubygems.org/
@@ -178,7 +177,6 @@ GEM
       thor (~> 1.0, >= 1.2.2)
       zeitwerk (~> 2.6)
     rake (13.1.0)
-    rbtree (0.4.6)
     rdoc (6.6.0)
       psych (>= 4.0.0)
     redcarpet (3.6.0)
@@ -205,10 +203,6 @@ GEM
       rspec-mocks (~> 3.12)
       rspec-support (~> 3.12)
     rspec-support (3.12.1)
-    set (1.0.3)
-    sorted_set (1.0.3)
-      rbtree
-      set (~> 1.0)
     stackprof (0.2.25)
     stringio (3.0.9)
     thor (1.3.0)
diff --git a/gemfiles/rails7.2.gemfile.lock b/gemfiles/rails7.2.gemfile.lock
index 1eb2890..30f1769 100644
--- a/gemfiles/rails7.2.gemfile.lock
+++ b/gemfiles/rails7.2.gemfile.lock
@@ -12,7 +12,6 @@ PATH
   specs:
     curly-templates (3.4.0)
       actionpack (>= 6.1)
-      sorted_set
 
 GEM
   remote: https://rubygems.org/
@@ -176,7 +175,6 @@ GEM
       thor (~> 1.0, >= 1.2.2)
       zeitwerk (~> 2.6)
     rake (13.2.1)
-    rbtree (0.4.6)
     rdoc (6.10.0)
       psych (>= 4.0.0)
     redcarpet (3.6.0)
@@ -204,10 +202,6 @@ GEM
       rspec-support (~> 3.13)
     rspec-support (3.13.2)
     securerandom (0.4.1)
-    set (1.1.1)
-    sorted_set (1.0.3)
-      rbtree
-      set (~> 1.0)
     stackprof (0.2.26)
     stringio (3.1.2)
     thor (1.3.2)
@@ -243,4 +237,4 @@ DEPENDENCIES
   yard-tomdoc
 
 BUNDLED WITH
-   2.5.17
+  4.0.3
diff --git a/gemfiles/rails8.0.gemfile.lock b/gemfiles/rails8.0.gemfile.lock
index bb7ed22..69c48bc 100644
--- a/gemfiles/rails8.0.gemfile.lock
+++ b/gemfiles/rails8.0.gemfile.lock
@@ -12,7 +12,6 @@ PATH
   specs:
     curly-templates (3.4.0)
       actionpack (>= 6.1)
-      sorted_set
 
 GEM
   remote: https://rubygems.org/
@@ -176,7 +175,6 @@ GEM
       thor (~> 1.0, >= 1.2.2)
       zeitwerk (~> 2.6)
     rake (13.2.1)
-    rbtree (0.4.6)
     rdoc (6.10.0)
       psych (>= 4.0.0)
     redcarpet (3.6.0)
@@ -204,10 +202,6 @@ GEM
       rspec-support (~> 3.13)
     rspec-support (3.13.2)
     securerandom (0.4.1)
-    set (1.1.1)
-    sorted_set (1.0.3)
-      rbtree
-      set (~> 1.0)
     stackprof (0.2.26)
     stringio (3.1.2)
     thor (1.3.2)
@@ -244,4 +238,4 @@ DEPENDENCIES
   yard-tomdoc
 
 BUNDLED WITH
-   2.5.17
+  4.0.3
diff --git a/lib/curly/presenter.rb b/lib/curly/presenter.rb
index e5487b7..c951639 100644
--- a/lib/curly/presenter.rb
+++ b/lib/curly/presenter.rb
@@ -1,5 +1,4 @@
 require 'curly/presenter_name_error'
-require "sorted_set"
 
 module Curly
 
@@ -246,23 +245,23 @@ def available_components
       #   Posts::ShowPresenter.dependencies
       #   #=> ['posts/comment', 'posts/comment_form']
       #
-      # Returns a Set of String view paths.
+      # Returns an Array of sorted view paths.
       def dependencies
         # The base presenter doesn't have any dependencies.
-        return SortedSet.new if self == Curly::Presenter
+        return [] if self == Curly::Presenter
 
-        @dependencies ||= SortedSet.new
-        @dependencies.union(superclass.dependencies)
+        @dependencies ||= []
+        @dependencies = @dependencies.union(superclass.dependencies).uniq.sort
       end
 
-      # Indicate that the presenter depends a list of other views.
+      # Indicate that the presenter depends on a list of other views.
       #
-      # deps - A list of String view paths that the presenter depends on.
+      # dependencies - A list of String view paths that the presenter depends on.
       #
-      # Returns nothing.
+      # Returns updated Array of String view paths.
       def depends_on(*dependencies)
-        @dependencies ||= SortedSet.new
-        @dependencies.merge(dependencies)
+        @dependencies ||= []
+        @dependencies = @dependencies.union(dependencies).uniq.sort
       end
 
       # Get or set the version of the presenter.
diff --git a/spec/presenter_spec.rb b/spec/presenter_spec.rb
index 9ea3892..6ea2353 100644
--- a/spec/presenter_spec.rb
+++ b/spec/presenter_spec.rb
@@ -226,6 +226,29 @@ class SubNestedPresenter < Curly::Presenter
       expect(cache_key).to eq "Foo::BarPresenter/42/Foo::BumPresenter/1337"
     end
 
+    it "includes the cache keys of all presenters in the dependency list" do
+      presenter = Class.new(Curly::Presenter) do
+        version 42
+        depends_on 'foo/bum'
+        depends_on 'foo/aum'
+      end
+
+      dependency = Class.new(Curly::Presenter) do
+        version 1337
+      end
+
+      dependency_2 = Class.new(Curly::Presenter) do
+        version 1338
+      end
+
+      stub_const("Foo::BarPresenter", presenter)
+      stub_const("Foo::BumPresenter", dependency)
+      stub_const("Foo::AumPresenter", dependency_2)
+
+      cache_key = Foo::BarPresenter.cache_key
+      expect(cache_key).to eq "Foo::BarPresenter/42/Foo::AumPresenter/1338/Foo::BumPresenter/1337"
+    end
+
     it "uses the view path of a dependency if there is no presenter for it" do
       presenter = Class.new(Curly::Presenter) do
         version 42
@@ -249,7 +272,14 @@ class SubNestedPresenter < Curly::Presenter
       Curly::Presenter.dependencies
       parent = Class.new(Curly::Presenter) { depends_on 'foo' }
       presenter = Class.new(parent) { depends_on 'bar' }
-      expect(presenter.dependencies.to_a).to match_array ['foo', 'bar']
+      expect(presenter.dependencies).to eq ['bar', 'foo']
+    end
+
+    it "doesn’t include duplicates" do
+      Curly::Presenter.dependencies
+      parent = Class.new(Curly::Presenter) { depends_on 'foo' }
+      presenter = Class.new(parent) { depends_on 'bar'; depends_on 'foo' }
+      expect(presenter.dependencies).to eq ['bar', 'foo']
     end
   end
 end