--- coregrind/pub_core_aspacemgr.h.orig
+++ coregrind/pub_core_aspacemgr.h
@@ -242,6 +242,9 @@ extern SysRes VG_(am_mmap_anon_float_client) ( SizeT length,
 Int prot );
    segment array accordingly.  This is fundamentally how V allocates
    itself more address space when needed. */
 extern SysRes VG_(am_mmap_anon_float_valgrind)( SizeT cszB );
+#if defined(__OpenBSD__)
+extern SysRes VG_(am_mmap_anon_float_valgrind_stack)( SizeT cszB );
+#endif

 /* Map privately a file at an unconstrained address for V, and update the
    segment array accordingly.  This is used by V for transiently
