diff --git a/src/c/a5/addsub.asm b/src/c/a5/addsub.asm
index 06071f1..5057f2d 100644
--- a/src/c/a5/addsub.asm
+++ b/src/c/a5/addsub.asm
@@ -14,11 +14,11 @@ addsub:
 
     mov eax, 0
 
-    mov operation, word [ebp+16]
+    mov [operation], word [ebp+16]
 
     add ax, word [ebp+8]
 
-    cmp operation, 0x2b
+    cmp [operation], 0x2b
     jne substract
 
     add ax, word [ebp-12]