diff --git a/src/arch/x86/isa/bitfields.isa b/src/arch/x86/isa/bitfields.isa
index e4a5e310c..c7ed02f2c 100644
--- a/src/arch/x86/isa/bitfields.isa
+++ b/src/arch/x86/isa/bitfields.isa
@@ -87,3 +87,4 @@ def bitfield SIB_INDEX sib.index;
 def bitfield SIB_BASE sib.base;
 
 def bitfield OPSIZE opSize;
+def bitfield ADDRSIZE addrSize;
diff --git a/src/arch/x86/types.hh b/src/arch/x86/types.hh
index 022f20ee5..225258358 100644
--- a/src/arch/x86/types.hh
+++ b/src/arch/x86/types.hh
@@ -149,7 +149,8 @@ namespace X86ISA
 
         //The effective operand size.
         uint8_t opSize;
-        //The
+        //The effective address size.
+        uint8_t addrSize;
     };
 
     inline static std::ostream &