diff --git a/bignum.c b/bignum.c
index 132b611be1..ddb1636d69 100644
--- a/bignum.c
+++ b/bignum.c
@@ -856,8 +856,6 @@ static VALUE
 rb_big_eq(x, y)
     VALUE x, y;
 {
-    double d;
-
     switch (TYPE(y)) {
       case T_FIXNUM:
 	y = rb_int2big(FIX2LONG(y));