diff --git a/lib/propshaft/assembly.rb b/lib/propshaft/assembly.rb
index 3fbb11c..7ca5b94 100644
--- a/lib/propshaft/assembly.rb
+++ b/lib/propshaft/assembly.rb
@@ -18,6 +18,10 @@ def load_path
     @load_path ||= Propshaft::LoadPath.new(config.paths, version: config.version)
   end
 
+  def application_stylesheets_load_path
+    @application_stylesheets_load_path ||= Propshaft::LoadPath.new([File.join(Rails.root, "app", "assets", "stylesheets")], version: config.version)
+  end
+
   def resolver
     @resolver ||= if manifest_path.exist?
       Propshaft::Resolver::Static.new manifest_path: manifest_path, prefix: config.prefix
diff --git a/lib/propshaft/helper.rb b/lib/propshaft/helper.rb
index 66e8d25..34a69c1 100644
--- a/lib/propshaft/helper.rb
+++ b/lib/propshaft/helper.rb
@@ -7,15 +7,15 @@ def compute_asset_path(path, options = {})
     # Add an option to call `stylesheet_link_tag` with `:all` to include every css file found on the load path.
     def stylesheet_link_tag(*sources, **options)
       if sources.first == :all
-        super(*all_stylesheets_paths, **options)
+        super(*all_application_stylesheets_paths, **options)
       else
         super
       end
     end
 
-    # Returns a sorted and unique array of logical paths for all stylesheets in the load path.
-    def all_stylesheets_paths
-      Rails.application.assets.load_path
+    # Returns a sorted and unique array of logical paths for all stylesheets only in the application stylesheets load path.
+    def all_application_stylesheets_paths
+      Rails.application.assets.application_stylesheets_load_path
         .assets(content_types: [ Mime::EXTENSION_LOOKUP["css"] ])
         .collect { |css| css.logical_path.to_s }
         .sort
diff --git a/test/dummy/config/application.rb b/test/dummy/config/application.rb
index fb160a1..9a01256 100644
--- a/test/dummy/config/application.rb
+++ b/test/dummy/config/application.rb
@@ -31,5 +31,6 @@ class Application < Rails::Application
     #
     # config.time_zone = "Central Time (US & Canada)"
     # config.eager_load_paths << Rails.root.join("extras")
+    config.assets.paths << File.join(Rails.root, "vendor", "stylesheets")
   end
 end
diff --git a/test/dummy/vendor/stylesheets/library.css b/test/dummy/vendor/stylesheets/library.css
new file mode 100644
index 0000000..e69de29
diff --git a/test/propshaft_integration_test.rb b/test/propshaft_integration_test.rb
index 554303d..b5d3222 100644
--- a/test/propshaft_integration_test.rb
+++ b/test/propshaft_integration_test.rb
@@ -8,6 +8,7 @@ class PropshaftIntegrationTest < ActionDispatch::IntegrationTest
 
     assert_select 'link[href="/assets/hello_world-4137140a.css"][data-custom-attribute="true"]'
     assert_select 'link[href="/assets/goodbye-b1dc9940.css"][data-custom-attribute="true"]'
+    assert_select 'link[href="/assets/library-356a192b.css"][data-custom-attribute="true"]', 0
 
     assert_select 'script[src="/assets/hello_world-888761f8.js"]'
   end