diff --git a/lib/hanami/action.rb b/lib/hanami/action.rb
index af842582..73ef78e1 100644
--- a/lib/hanami/action.rb
+++ b/lib/hanami/action.rb
@@ -67,7 +67,11 @@ def self.gem_loader
       cookie_options.to_h.compact
     }
     setting :root_directory, constructor: -> (dir) {
-      Pathname(File.expand_path(dir || Dir.pwd)).realpath
+      if Hanami.respond_to?(:app) && Hanami.app
+        Hanami.app.root
+      else
+        Pathname(File.expand_path(dir || Dir.pwd)).realpath
+      end
     }
     setting :public_directory, default: Config::DEFAULT_PUBLIC_DIRECTORY
     setting :before_callbacks, default: Utils::Callbacks::Chain.new, mutable: true
diff --git a/spec/unit/hanami/action/config_spec.rb b/spec/unit/hanami/action/config_spec.rb
index 3d2b187f..743865e5 100644
--- a/spec/unit/hanami/action/config_spec.rb
+++ b/spec/unit/hanami/action/config_spec.rb
@@ -95,6 +95,22 @@
         config.root_directory = "/non-existent"
       }.to raise_error(StandardError)
     end
+
+    context "within a Hanami app" do
+      before do
+        app = double("Hanami.app", root: root_directory)
+
+        allow(Hanami).to receive(:respond_to?).with(:app, true).and_return(true)
+        allow(Hanami).to receive(:respond_to?).with(:app).and_return(true)
+        allow(Hanami).to receive(:app).and_return(app)
+      end
+
+      let(:root_directory) { Pathname.new(__dir__).join("spec") }
+
+      it "returns the Hanami app root" do
+        expect(config.root_directory).to eq(root_directory)
+      end
+    end
   end
 
   describe "public_directory" do