diff --git a/include/cppgc/internal/caged-heap-local-data.h b/include/cppgc/internal/caged-heap-local-data.h
index b901cbfec3..4bb224e4f5 100644
--- a/include/cppgc/internal/caged-heap-local-data.h
+++ b/include/cppgc/internal/caged-heap-local-data.h
@@ -19,6 +19,8 @@
 #include <bit>
 #endif  // __cpp_lib_bitopts
 
+#if defined(CPPGC_CAGED_HEAP)
+
 namespace cppgc {
 namespace internal {
 
@@ -102,4 +104,6 @@ struct CagedHeapLocalData final {
 }  // namespace internal
 }  // namespace cppgc
 
+#endif  // defined(CPPGC_CAGED_HEAP)
+
 #endif  // INCLUDE_CPPGC_INTERNAL_CAGED_HEAP_LOCAL_DATA_H_