diff --git a/avr/common/multiply.asm b/avr/common/multiply.asm
index 61834c2..13e682c 100644
--- a/avr/common/multiply.asm
+++ b/avr/common/multiply.asm
@@ -39,8 +39,8 @@ Utils_Mulu16x16_32_loop:
     lsr r23
     ror r22
     brcc Utils_Mulu16x16_32_noadd ; current digit in B is 0, don't add shifted A to result
-    add r16, r22
-    adc r17, r23
+    add r16, r20
+    adc r17, r21
     adc r18, r24
     adc r19, r25
 ;    brcs Utils_Mulu16x16_32_overflow ; can't happen