diff --git a/lib/simple_navigation/adapters.rb b/lib/simple_navigation/adapters.rb
new file mode 100644
index 0000000..1f451be
--- /dev/null
+++ b/lib/simple_navigation/adapters.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module SimpleNavigation
+  # Explicit namespace for the framework adapters living in adapters/.
+  #
+  # Without this file Zeitwerk would infer SimpleNavigation::Adapters as an
+  # implicit namespace from the adapters/ directory. That inference is not
+  # resolved reliably on every runtime (e.g. JRuby, see issue #237), so the
+  # namespace is defined explicitly here.
+  module Adapters
+  end
+end
diff --git a/lib/simple_navigation/renderer.rb b/lib/simple_navigation/renderer.rb
new file mode 100644
index 0000000..a127147
--- /dev/null
+++ b/lib/simple_navigation/renderer.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module SimpleNavigation
+  # Explicit namespace for the renderers living in renderer/.
+  #
+  # Without this file Zeitwerk would infer SimpleNavigation::Renderer as an
+  # implicit namespace from the renderer/ directory. That inference is not
+  # resolved reliably on every runtime (e.g. JRuby, see issue #237), so the
+  # namespace is defined explicitly here.
+  module Renderer
+  end
+end