diff --git a/src/stub/macros.ash b/src/stub/macros.ash
index b0d039bb..d8d7f408 100644
--- a/src/stub/macros.ash
+++ b/src/stub/macros.ash
@@ -128,7 +128,7 @@ ct1:
  %endif
                 mov     [edi], eax
                 add     edi, byte 5
-                mov     eax, ebx
+                mov     al, bl
                 loop    ct1
 %else;  __CALLTR10__
 ;; 32-bit call XOR jump trick