diff --git a/src/arch/x86/isa/operands.isa b/src/arch/x86/isa/operands.isa
index 4b144dce0..20376f38f 100644
--- a/src/arch/x86/isa/operands.isa
+++ b/src/arch/x86/isa/operands.isa
@@ -96,4 +96,7 @@ def operand_types {{
 }};
 
 def operands {{
+        # This is just copied from SPARC, because having no operands confuses
+        # the parser.
+        'Rd':               ('IntReg', 'udw', 'RD', 'IsInteger', 1)
 }};