1 files changed, 3 insertions, 3 deletions
diff --git a/gc.c b/gc.c
index 8f4473759c..d3c87ddc8f 100644
--- a/gc.c
+++ b/gc.c
@@ -1938,15 +1938,15 @@ id2ref(VALUE obj, VALUE objid)
     if (ptr == Qfalse) return Qfalse;
     if (ptr == Qnil) return Qnil;
     if (FIXNUM_P(ptr)) return (VALUE)ptr;
+    ptr = objid ^ FIXNUM_FLAG;	/* unset FIXNUM_FLAG */
 
-    if ((objid % sizeof(RVALUE)) == (4 << 2)) {
-        ID symid = objid / sizeof(RVALUE);
+    if ((ptr % sizeof(RVALUE)) == (4 << 2)) {
+        ID symid = ptr / sizeof(RVALUE);
         if (rb_id2name(symid) == 0)
             rb_raise(rb_eRangeError, "%p is not symbol id value", p0);
         return ID2SYM(symid);
     }
 
-    ptr = objid ^ FIXNUM_FLAG;	/* unset FIXNUM_FLAG */
     if (!is_pointer_to_heap((void *)ptr)|| BUILTIN_TYPE(ptr) >= T_BLOCK) {
 	rb_raise(rb_eRangeError, "%p is not id value", p0);
     }