diff --git a/thread.c b/thread.c
index 8d7d538328..a0ff595446 100644
--- a/thread.c
+++ b/thread.c
@@ -438,7 +438,7 @@ thread_initialize(VALUE thread, VALUE args)
         if (!proc || !RTEST(loc = rb_proc_location(proc))) {
             rb_raise(rb_eThreadError, "already initialized thread");
         }
-	fn = RSTRING_PTR(RARRAY_PTR(loc)[0]);
+	file = RSTRING_PTR(RARRAY_PTR(loc)[0]);
 	if (NIL_P(line = RARRAY_PTR(loc)[1])) {
 	    rb_raise(rb_eThreadError, "already initialized thread - %s",
 		     file);