diff --git a/common/h/registers/x86_64_regs.h b/common/h/registers/x86_64_regs.h
index 9fc55773bc..61bda15af6 100644
--- a/common/h/registers/x86_64_regs.h
+++ b/common/h/registers/x86_64_regs.h
@@ -132,6 +132,7 @@ namespace Dyninst { namespace x86_64 {
   const signed int FLAGC = x86::FLAGC; // I/O Privilege Level (bits 12 and 13)
   const signed int FLAGD = x86::FLAGD; // I/O Privilege Level (bits 12 and 13)
   const signed int NT    = x86::NT;    // Nested Task
+  const signed int FLAGF = x86::FLAGF; // Reserved
   const signed int RF    = x86::RF;    // Resume Flag
 
   //          (      name,     ID | alias |   cat |        arch,     arch)
@@ -221,6 +222,7 @@ namespace Dyninst { namespace x86_64 {
   DEF_REGISTER(     flagc,  FLAGC |   BIT |  FLAG | Arch_x86_64, "x86_64");
   DEF_REGISTER(     flagd,  FLAGD |   BIT |  FLAG | Arch_x86_64, "x86_64");
   DEF_REGISTER(       nt_,     NT |   BIT |  FLAG | Arch_x86_64, "x86_64");
+  DEF_REGISTER(     flagf,  FLAGF |   BIT |  FLAG | Arch_x86_64, "x86_64");
   DEF_REGISTER(        rf,     RF |   BIT |  FLAG | Arch_x86_64, "x86_64");
   DEF_REGISTER(        ds, BASEDS |  FULL |   SEG | Arch_x86_64, "x86_64");
   DEF_REGISTER(        es, BASEES |  FULL |   SEG | Arch_x86_64, "x86_64");
diff --git a/common/src/registers/MachRegister.C b/common/src/registers/MachRegister.C
index fe65216be1..db8c328a16 100644
--- a/common/src/registers/MachRegister.C
+++ b/common/src/registers/MachRegister.C
@@ -800,6 +800,7 @@ namespace Dyninst {
               case x86_64::OF: n = x86_flag_of; break;
               case x86_64::FLAGC: n = x86_flag_iopl0; break;
               case x86_64::FLAGD: n = x86_flag_iopl1; break;
+              case x86_64::FLAGF: n = x86_flag_15; break;
               default:
                 c = -1;
                 return;
diff --git a/dataflowAPI/src/SymEvalPolicy.C b/dataflowAPI/src/SymEvalPolicy.C
index 76f1a198e3..3aa5351c0a 100644
--- a/dataflowAPI/src/SymEvalPolicy.C
+++ b/dataflowAPI/src/SymEvalPolicy.C
@@ -480,6 +480,8 @@ Absloc SymEvalPolicy_64::convert(X86Flag f)
          return Absloc(x86_64::FLAGD);
       case x86_flag_nt:
          return Absloc(x86_64::nt_);
+      case x86_flag_15:
+         return Absloc(x86_64::FLAGF);
       default:
          assert(0);
          return Absloc();