diff --git a/include/rawrtc/utils.h b/include/rawrtc/utils.h
new file mode 100644
index 0000000..94f63b9
--- /dev/null
+++ b/include/rawrtc/utils.h
@@ -0,0 +1,10 @@
+#pragma once
+#include <re.h>
+
+/*
+ * Array container.
+ */
+struct rawrtc_array_container {
+    size_t n_items;
+    void* items[];
+};