diff --git a/src/isa/x86/exec/arith.h b/src/isa/x86/exec/arith.h
index 79c74b4432130a030d7ab56673fb63c534bb0436..5e53c463be7da48875f2e55d9a04290222eeed88 100644
--- a/src/isa/x86/exec/arith.h
+++ b/src/isa/x86/exec/arith.h
@@ -112,10 +112,15 @@ static inline make_EHelper(adc) {
     rtl_andi(s, s1, s1, 0xffffffffu >> ((4 - id_dest->width) * 8));
   }
   rtl_update_ZFSF(s, s1, id_dest->width);
-  rtl_is_add_overflow(s, s0, s1, ddest, s0, id_dest->width);
-  rtl_set_OF(s, s0);
-  rtl_is_add_carry(s, s0, s1, ddest);
+  // s1 = ddest + (dsrc1 + CF)
+  // new_CF = (CF ? s1 <= dsrc1 : s1 < dsrc1);
+  //        = (CF ? s1 < dsrc1 + 1 : s1 < dsrc1);
+  //        = s1 < dsrc1 + CF;
+  //        = s1 < s0;
+  rtl_setrelop(s, RELOP_LTU, s0, s1, s0);
   rtl_set_CF(s, s0);
+  rtl_is_add_overflow(s, s0, s1, ddest, dsrc1, id_dest->width);
+  rtl_set_OF(s, s0);
 #endif
   operand_write(s, id_dest, s1);
   print_asm_template2(adc);
@@ -137,10 +142,15 @@ static inline make_EHelper(sbb) {
     rtl_andi(s, s1, s1, 0xffffffffu >> ((4 - id_dest->width) * 8));
   }
   rtl_update_ZFSF(s, s1, id_dest->width);
-  rtl_is_sub_overflow(s, s0, s1, ddest, s0, id_dest->width);
-  rtl_set_OF(s, s0);
-  rtl_is_sub_carry(s, s0, s1, ddest);
+  // s1 = ddest - (dsrc1 + CF)
+  // new_CF = (CF ? ddest <= dsrc1 : ddest < dsrc1);
+  //        = (CF ? ddest < dsrc1 + 1 : ddest < dsrc1);
+  //        = ddest < dsrc1 + CF;
+  //        = ddest < s0;
+  rtl_setrelop(s, RELOP_LTU, s0, ddest, s0);
   rtl_set_CF(s, s0);
+  rtl_is_sub_overflow(s, s0, s1, ddest, dsrc1, id_dest->width);
+  rtl_set_OF(s, s0);
 #endif
   operand_write(s, id_dest, s1);
   print_asm_template2(sbb);
diff --git a/src/isa/x86/exec/exec.c b/src/isa/x86/exec/exec.c
index f24f39115c72b9a700edf72f9f3bcfedfa42741a..35e885e46703a4b8ef4f532a17bf3e594f212a88 100644
--- a/src/isa/x86/exec/exec.c
+++ b/src/isa/x86/exec/exec.c
@@ -110,13 +110,13 @@ IDEXW(0x00, G2E, add, 1)    IDEX (0x01, G2E, add)       IDEXW(0x02, E2G, add, 1)
 EMPTY(0x04)                 IDEX (0x05, I2a, add)
 IDEXW(0x08, G2E, or, 1)     IDEX (0x09, G2E, or)        IDEXW(0x0a, E2G, or, 1)     IDEX (0x0b, E2G, or)
 IDEXW(0x0c, I2a, or, 1)     IDEX (0x0d, I2a, or)        EMPTY(0x0e)                 EX   (0x0f, 2byte_esc)
-EMPTY(0x10)                 IDEX (0x11, G2E, adc)       EMPTY(0x12)                 IDEX (0x13, E2G, adc)
+IDEXW(0x10, G2E, adc, 1)    IDEX (0x11, G2E, adc)       EMPTY(0x12)                 IDEX (0x13, E2G, adc)
 
-EMPTY(0x18)                 IDEX (0x19, G2E, sbb)       EMPTY(0x1a)                 IDEX (0x1b, E2G, sbb)
+IDEXW(0x18, G2E, sbb, 1)    IDEX (0x19, G2E, sbb)       EMPTY(0x1a)                 IDEX (0x1b, E2G, sbb)
 
 IDEXW(0x20, G2E, and, 1)    IDEX (0x21, G2E, and)       IDEXW(0x22, E2G, and, 1)    IDEX (0x23, E2G, and)
 IDEXW(0x24, I2a, and, 1)    IDEX (0x25, I2a, and)
-EMPTY(0x28)                 IDEX (0x29, G2E, sub)       EMPTY(0x2a)                 IDEX (0x2b, E2G, sub)
+IDEXW(0x28, G2E, sub, 1)    IDEX (0x29, G2E, sub)       EMPTY(0x2a)                 IDEX (0x2b, E2G, sub)
 EMPTY(0x2c)                 IDEX (0x2d, I2a, sub)
 IDEXW(0x30, G2E, xor, 1)    IDEX (0x31, G2E, xor)       IDEXW(0x32, E2G, xor, 1)    IDEX (0x33, E2G, xor)
 EMPTY(0x34)                 IDEX (0x35, I2a, xor)