So much for C's "type system" (ha ha).  Correct version of r7250.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@7251 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/helgrind/hg_main.c b/helgrind/hg_main.c
index d9deacd..5415d17 100644
--- a/helgrind/hg_main.c
+++ b/helgrind/hg_main.c
@@ -6241,7 +6241,7 @@
          HG_(deleteBag)( lk->heldBy );
          lk->heldBy = NULL;
          lk->heldW = False;
-         lk->acquired_at = False;
+         lk->acquired_at = NULL;
       }
       tl_assert( !lk->heldBy );
       tl_assert( is_sane_LockN(lk) );