diff --git a/src/H5PartPrivate.h b/src/H5PartPrivate.h
index f2f2bee..2e2d47c 100644
--- a/src/H5PartPrivate.h
+++ b/src/H5PartPrivate.h
@@ -21,6 +21,11 @@ struct _iter_op_data {
 	char *pattern;
 };
 
+h5part_int64_t
+_H5Part_get_num_particles (
+	H5PartFile *f
+	);
+
 herr_t
 _H5Part_iteration_operator (
 	hid_t group_id,