1 files changed, 1 insertions, 1 deletions
diff --git a/io.c b/io.c
index 2e4c335aae..e2f6875c3e 100644
--- a/io.c
+++ b/io.c
@@ -4543,7 +4543,7 @@ rb_io_ungetc(VALUE io, VALUE c)
     if (FIXNUM_P(c)) {
 	c = rb_enc_uint_chr(FIX2UINT(c), io_read_encoding(fptr));
     }
-    else if (RB_TYPE_P(c, T_BIGNUM)) {
+    else if (RB_BIGNUM_TYPE_P(c)) {
 	c = rb_enc_uint_chr(NUM2UINT(c), io_read_encoding(fptr));
     }
     else {