Use qstr id to create sys module.
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index 7efa85b..bf575e2 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -81,6 +81,7 @@
 Q(sorted)
 Q(sum)
 Q(str)
+Q(sys)
 Q(tuple)
 Q(type)
 Q(zip)
diff --git a/py/runtime.c b/py/runtime.c
index 0f27273..c84a28e 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -168,7 +168,7 @@
 
 #if MICROPY_CPYTHON_COMPAT
     // Precreate sys module, so "import sys" didn't throw exceptions.
-    mp_obj_new_module(QSTR_FROM_STR_STATIC("sys"));
+    mp_obj_new_module(MP_QSTR_sys);
 #endif
 
     mp_module_micropython_init();