diff --git a/src/arch/x86/isa/microops/regop.isa b/src/arch/x86/isa/microops/regop.isa
index 1aa7c510b3..e3ad164ebc 100644
--- a/src/arch/x86/isa/microops/regop.isa
+++ b/src/arch/x86/isa/microops/regop.isa
@@ -768,7 +768,7 @@ let {{
                 uint64_t top = flags.cf << (dataSize * 8 - shiftAmt);
                 if(shiftAmt > 1)
                     top |= psrc1 << (dataSize * 8 - shiftAmt + 1);
-                uint64_t bottom = bits(psrc1, dataSize * 8, shiftAmt);
+                uint64_t bottom = bits(psrc1, dataSize * 8 - 1, shiftAmt);
                 DestReg = merge(DestReg, top | bottom, dataSize);
             }
             else