diff --git a/src/dynarec/arm64/dynarec_arm64_0f.c b/src/dynarec/arm64/dynarec_arm64_0f.c
index e3ac683ef..813ea8bea 100644
--- a/src/dynarec/arm64/dynarec_arm64_0f.c
+++ b/src/dynarec/arm64/dynarec_arm64_0f.c
@@ -87,17 +87,25 @@ uintptr_t dynarec64_0F(dynarec_arm_t* dyn, uintptr_t addr, uintptr_t ip, int nin
                         addr = geted(dyn, addr, ninst, nextop, &wback, x2, &fixedaddress, NULL, 0, 0, rex, NULL, 0, 0);
                         MOV32w(x1, 0x7f);
                         STURH_I9(x1, wback, 0);
-                        MOV32w(x1, 0x000c);
-                        STURH_I9(x1, wback, 2);
-                        MOV32w(x1, 0xd000);
-                        STURH_I9(x1, wback, 4);
+                        if(rex.is32bits) {
+                            MOV32w(x1, 0x3000);
+                            STURw_I9(x1, wback, 2);
+                        } else {
+                            MOV64x(x1, 0xfffffe0000077000LL);
+                            STURx_I9(x1, wback, 2);
+                        }
                         break;
                     case 1:
                         INST_NAME("SIDT Ed");
                         addr = geted(dyn, addr, ninst, nextop, &wback, x2, &fixedaddress, NULL, 0, 0, rex, NULL, 0, 0);
                         MOV32w(x1, 0xfff);
                         STURH_I9(x1, wback, 0);
-                        STURw_I9(xZR, wback, 2);
+                        if(rex.is32bits) {
+                            STURw_I9(xZR, wback, 2);
+                        } else {
+                            MOV64x(x1, 0xfffffe0000000000LL);
+                            STURx_I9(x1, wback, 2);
+                        }
                         break;
                     case 4:
                         INST_NAME("SMSW Ew");
diff --git a/src/emu/x64run0f.c b/src/emu/x64run0f.c
index 83b60043e..d0b5900f8 100644
--- a/src/emu/x64run0f.c
+++ b/src/emu/x64run0f.c
@@ -101,13 +101,19 @@ uintptr_t Run0F(x64emu_t *emu, rex_t rex, uintptr_t addr, int *step)
                 switch((nextop>>3)&7) {
                     case 0:                 /* SGDT Ed */
                         ED->word[0] = 0x7f;    // dummy return...
-                        ED->word[1] = 0x000c;
-                        ED->word[2] = 0xd000;
+                        if(rex.is32bits) {
+                            *(uint32_t*)(&ED->word[1]) = 0x3000;
+                        } else {
+                            *(uint64_t*)(&ED->word[1]) = 0xfffffe0000077000LL;
+                        }
                         break;
                     case 1:                 /* SIDT Ed */
                         ED->word[0] = 0xfff;    // dummy return, like "disabled"
-                        ED->word[1] = 0;
-                        ED->word[2] = 0;
+                        if(rex.is32bits) {
+                            *(uint32_t*)(&ED->word[1]) = 0x0000;
+                        } else {
+                            *(uint64_t*)(&ED->word[1]) = 0xfffffe0000000000LL;
+                        }
                         break;
                     case 4:                 /* SMSW Ew */
                         // dummy for now... Do I need to track CR0 state?