diff --git a/common/h/registers/x86_64_regs.h b/common/h/registers/x86_64_regs.h
index 6ac91fa9c6..01143f53c6 100644
--- a/common/h/registers/x86_64_regs.h
+++ b/common/h/registers/x86_64_regs.h
@@ -61,6 +61,7 @@ namespace Dyninst { namespace x86_64 {
   const signed int OCT    = 0x00000800; // 128-bit SSE, FC16, XOP, AVX, and FMA3/4
   const signed int YMMS   = 0x00000900; // 256-bit SSE, AVX2, FMA3/4
   const signed int ZMMS   = 0x00000A00; // 512-bit AVX-512/AVX10
+  const signed int KMSKS  = 0x00000B00;  // 64-bit mask from AVX-512/AVX10
 
   /* Register Categories */
   const signed int GPR    = 0x00010000;  // General-Purpose Registers
@@ -239,14 +240,14 @@ namespace Dyninst { namespace x86_64 {
   DEF_REGISTER(      orax,    0x0 |  FULL |  MISC | Arch_x86_64, "x86_64");
   DEF_REGISTER(    fsbase,    0x1 |  FULL |  MISC | Arch_x86_64, "x86_64");
   DEF_REGISTER(    gsbase,    0x2 |  FULL |  MISC | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k0,   0x00 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k1,   0x01 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k2,   0x02 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k3,   0x03 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k4,   0x04 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k5,   0x05 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k6,   0x06 |   OCT | KMASK | Arch_x86_64, "x86_64");
-  DEF_REGISTER(        k7,   0x07 |   OCT | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k0,   0x00 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k1,   0x01 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k2,   0x02 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k3,   0x03 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k4,   0x04 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k5,   0x05 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k6,   0x06 | KMSKS | KMASK | Arch_x86_64, "x86_64");
+  DEF_REGISTER(        k7,   0x07 | KMSKS | KMASK | Arch_x86_64, "x86_64");
   DEF_REGISTER(      xmm0,   0x00 |   OCT |   XMM | Arch_x86_64, "x86_64");
   DEF_REGISTER(      xmm1,   0x01 |   OCT |   XMM | Arch_x86_64, "x86_64");
   DEF_REGISTER(      xmm2,   0x02 |   OCT |   XMM | Arch_x86_64, "x86_64");
diff --git a/common/src/registers/MachRegister.C b/common/src/registers/MachRegister.C
index abe49dcf58..2db23ed3bd 100644
--- a/common/src/registers/MachRegister.C
+++ b/common/src/registers/MachRegister.C
@@ -137,6 +137,7 @@ namespace Dyninst {
           case x86_64::BIT: return 0;
           case x86_64::YMMS: return 32;
           case x86_64::ZMMS: return 64;
+          case x86_64::KMSKS: return 8;
           default:
             return 0;  // Xiaozhu: return 0 as an indication of parsing junk.
         }
@@ -1009,6 +1010,7 @@ namespace Dyninst {
           case x86_64::FULL:
           case x86_64::OCT:
           case x86_64::MMS:
+          case x86_64::KMSKS:
           case x86_64::FPDBL: p = x86_regpos_qword; break;
           case x86_64::H_REG: p = x86_regpos_high_byte; break;
           case x86_64::L_REG: p = x86_regpos_low_byte; break;