diff --git a/swtp6800/common/m6800.c b/swtp6800/common/m6800.c
index 26bf7dc7..b3de2480 100644
--- a/swtp6800/common/m6800.c
+++ b/swtp6800/common/m6800.c
@@ -1098,6 +1098,7 @@ t_stat sim_instr (void)
                 break;
             case 0x92:                  /* SBC A dir */
                 lo = (get_dir_val() + get_flag(CF)) & BYTEMASK; //RSV - fixed ordering problem
+                op1 = A;
                 A = A - lo;
                 COND_SET_FLAG_C(A);
                 A &= BYTEMASK;
@@ -1202,6 +1203,7 @@ t_stat sim_instr (void)
                 break;
             case 0xA2:                  /* SBC A ind */
                 lo = (get_indir_val() + get_flag(CF)) & BYTEMASK; //RSV - fixed ordering problem
+                op1 = A;
                 A = A - lo;
                 COND_SET_FLAG_C(A);
                 A &= BYTEMASK;