diff --git a/src/arch/arm/insts/static_inst.hh b/src/arch/arm/insts/static_inst.hh
index 4595646cb4..7ca1a84b68 100644
--- a/src/arch/arm/insts/static_inst.hh
+++ b/src/arch/arm/insts/static_inst.hh
@@ -440,7 +440,7 @@ class ArmStaticInst : public StaticInst
     MachInst
     encoding() const
     {
-        return static_cast<MachInst>(mask(instSize() * 8));
+        return static_cast<MachInst>(machInst & (mask(instSize() * 8)));
     }
 };
 }