1 files changed, 1 insertions, 1 deletions
diff --git a/io.c b/io.c
index c17fc9e93f..61cfa97b83 100644
--- a/io.c
+++ b/io.c
@@ -6103,7 +6103,7 @@ argf_set_encoding(int argc, VALUE *argv, VALUE io)
 {
     rb_io_t *fptr;
 
-    if (next_argv()) {
+    if (!next_argv()) {
 	rb_raise(rb_eArgError, "no stream to set encoding");
     }
     rb_io_set_encoding(argc, argv, current_file);