diff --git a/src/xdiff/xutils.h b/src/xdiff/xutils.h
index fba7bae..fd0bba9 100644
--- a/src/xdiff/xutils.h
+++ b/src/xdiff/xutils.h
@@ -42,6 +42,7 @@
 int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
 		       int line1, int count1, int line2, int count2);
 
-
+/* Do not call this function, use XDL_ALLOC_GROW instead */
+void* xdl_alloc_grow_helper(void* p, long nr, long* alloc, size_t size);
 
 #endif /* #if !defined(XUTILS_H) */