diff --git a/src/arch/x86/isa/insts/general_purpose/input_output/general_io.py b/src/arch/x86/isa/insts/general_purpose/input_output/general_io.py
index 27396e255b..58b38e537b 100644
--- a/src/arch/x86/isa/insts/general_purpose/input_output/general_io.py
+++ b/src/arch/x86/isa/insts/general_purpose/input_output/general_io.py
@@ -39,7 +39,7 @@
 microcode = '''
     def macroop IN_R_I {
         .adjust_imm trimImm(8)
-        limm t1, imm, dataSize=asz
+        limm t1, imm, dataSize=8
         mfence
         ld reg, intseg, [1, t1, t0], "IntAddrPrefixIO << 3", addressSize=8, \
             nonSpec=True