diff --git a/src/grib_accessor.h b/src/grib_accessor.h
new file mode 100644
index 000000000..f91b6312b
--- /dev/null
+++ b/src/grib_accessor.h
@@ -0,0 +1,5 @@
+# pragma once
+
+#include "grib_api_internal.h"
+
+template <typename T> int grib_unpack(grib_accessor* a, T* v, size_t* len);