diff --git a/ChangeLog b/ChangeLog
index 2f9218797f..c1db73b638 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Jul 31 00:10:20 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* proc.c (rb_proc_call_with_block): prevent null reference.
+
 Wed Jul 30 22:19:13 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* parse.y (vtable_free): remove meaningless null check.
diff --git a/proc.c b/proc.c
index 415ad1c201..59b3fd3abc 100644
--- a/proc.c
+++ b/proc.c
@@ -536,7 +536,7 @@ rb_proc_call_with_block(VALUE self, int argc, VALUE *argv, VALUE pass_procval)
     }
 
     return vm_invoke_proc(GET_THREAD(), proc, proc->block.self,
-			  argc, argv, &pass_proc->block);
+			  argc, argv, (pass_proc ? &pass_proc->block : 0));
 }
 
 /*