1 files changed, 1 insertions, 1 deletions
diff --git a/compile.c b/compile.c
index fd0af93c76..5ba4af476a 100644
--- a/compile.c
+++ b/compile.c
@@ -8062,7 +8062,7 @@ iseq_ibf_dump(const rb_iseq_t *iseq, VALUE opt)
 
     if (RTEST(opt)) {
 	VALUE opt_str = rb_check_string_type(opt);
-	header.extra_size = (unsigned int)RSTRING_LEN(opt_str) + 1;
+	header.extra_size = RSTRING_LENINT(opt_str) + 1;
 	ibf_dump_write(&dump, RSTRING_PTR(opt_str), header.extra_size);
     }
     else {