diff --git a/js/src/jit/IonBuilder.cpp b/js/src/jit/IonBuilder.cpp
index 7d47db5338e3..5d3459a71fe5 100644
--- a/js/src/jit/IonBuilder.cpp
+++ b/js/src/jit/IonBuilder.cpp
@@ -9265,11 +9265,6 @@ IonBuilder::jsop_setarg(uint32_t arg)
                     JS_ASSERT(op->resultTypeSet() == &argTypes[arg]);
                     if (!argTypes[arg].addType(types::Type::UnknownType(), alloc_->lifoAlloc()))
                         return false;
-                    if (val->isMul())
-                        val->setResultType(MIRType_Double);
-                    else
-                        JS_ASSERT(val->type() == MIRType_Int32);
-                    val->setResultTypeSet(nullptr);
                 }
             }
         }