1 files changed, 3 insertions, 0 deletions
diff --git a/io.c b/io.c
index 5d6d162c11..077d1c036e 100644
--- a/io.c
+++ b/io.c
@@ -9548,6 +9548,9 @@ opt_i_get(ID id, VALUE *var)
 static VALUE
 argf_inplace_mode_set(VALUE argf, VALUE val)
 {
+    if (rb_safe_level() >= 1 && OBJ_TAINTED(val))
+	rb_insecure_operation();
+
     if (!RTEST(val)) {
 	if (ARGF.inplace) free(ARGF.inplace);
 	ARGF.inplace = 0;