1 files changed, 1 insertions, 0 deletions

diff --git a/cpu/os.asm b/cpu/os.asm
index 4a7449a..fd8c50f 100644
--- a/cpu/os.asm
+++ b/cpu/os.asm
@@ -87,6 +87,7 @@ add_b_to_string:
     incri C 1
     sw C 0(D)
     pop A
+    jz A check_input
 check_input_ret:
     jr RA