diff --git a/extmod/modujson.c b/extmod/modujson.c
index 80fccc8a11..6b24bf5781 100644
--- a/extmod/modujson.c
+++ b/extmod/modujson.c
@@ -292,7 +292,11 @@ STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_loads_obj, mod_ujson_loads);
 
 STATIC const mp_rom_map_elem_t mp_module_ujson_globals_table[] = {
+#if CIRCUITPY
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_json) },
+#else
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ujson) },
+#endif
     { MP_ROM_QSTR(MP_QSTR_dump), MP_ROM_PTR(&mod_ujson_dump_obj) },
     { MP_ROM_QSTR(MP_QSTR_dumps), MP_ROM_PTR(&mod_ujson_dumps_obj) },
     { MP_ROM_QSTR(MP_QSTR_load), MP_ROM_PTR(&mod_ujson_load_obj) },
diff --git a/extmod/modure.c b/extmod/modure.c
index 6561362a8c..e2556c41b5 100644
--- a/extmod/modure.c
+++ b/extmod/modure.c
@@ -462,7 +462,11 @@ MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_re_sub_obj, 3, 5, mod_re_sub);
 #endif
 
 STATIC const mp_rom_map_elem_t mp_module_re_globals_table[] = {
+#if CIRCUITPY
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_re) },
+#else
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ure) },
+#endif
     { MP_ROM_QSTR(MP_QSTR_compile), MP_ROM_PTR(&mod_re_compile_obj) },
     { MP_ROM_QSTR(MP_QSTR_match), MP_ROM_PTR(&mod_re_match_obj) },
     { MP_ROM_QSTR(MP_QSTR_search), MP_ROM_PTR(&mod_re_search_obj) },
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index c70d52a7bb..bb43201d8e 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -33,6 +33,9 @@
 #ifndef __INCLUDED_MPCONFIG_CIRCUITPY_H
 #define __INCLUDED_MPCONFIG_CIRCUITPY_H
 
+// This is CircuitPython.
+#define CIRCUITPY 1
+
 // REPR_C encodes qstrs, 31-bit ints, and 30-bit floats in a single 32-bit word.
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
 
diff --git a/py/moduerrno.c b/py/moduerrno.c
index c5daae4687..7915603e4e 100644
--- a/py/moduerrno.c
+++ b/py/moduerrno.c
@@ -84,7 +84,11 @@ STATIC const mp_obj_dict_t errorcode_dict = {
 #endif
 
 STATIC const mp_rom_map_elem_t mp_module_uerrno_globals_table[] = {
+#if CIRCUITPY
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_errno) },
+#else
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uerrno) },
+#endif
     #if MICROPY_PY_UERRNO_ERRORCODE
     { MP_ROM_QSTR(MP_QSTR_errorcode), MP_ROM_PTR(&errorcode_dict) },
     #endif
diff --git a/py/mpconfig.h b/py/mpconfig.h
index bb7952a8b3..3ec383817e 100755
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -45,6 +45,11 @@
 #include <mpconfigport.h>
 #endif
 
+// Is this a CircuitPython build?
+#ifndef CIRCUITPY
+#define CIRCUITPY 0
+#endif
+
 // Any options not explicitly set in mpconfigport.h will get default
 // values below.
 
diff --git a/py/objmodule.c b/py/objmodule.c
index 9a56f48516..469a95976a 100644
--- a/py/objmodule.c
+++ b/py/objmodule.c
@@ -148,7 +148,11 @@ STATIC const mp_rom_map_elem_t mp_builtin_module_table[] = {
     { MP_ROM_QSTR(MP_QSTR_array), MP_ROM_PTR(&mp_module_array) },
 #endif
 #if MICROPY_PY_IO
+#if CIRCUITPY
     { MP_ROM_QSTR(MP_QSTR_io), MP_ROM_PTR(&mp_module_io) },
+#else
+    { MP_ROM_QSTR(MP_QSTR_uio), MP_ROM_PTR(&mp_module_io) },
+#endif
 #endif
 #if MICROPY_PY_COLLECTIONS
     { MP_ROM_QSTR(MP_QSTR_collections), MP_ROM_PTR(&mp_module_collections) },
@@ -179,9 +183,12 @@ STATIC const mp_rom_map_elem_t mp_builtin_module_table[] = {
     // extmod modules
 
 #if MICROPY_PY_UERRNO
+#if CIRCUITPY
 // CircuitPython: Defined in MICROPY_PORT_BUILTIN_MODULES, so not defined here.
 // TODO: move to shared-bindings/
-//    { MP_ROM_QSTR(MP_QSTR_uerrno), MP_ROM_PTR(&mp_module_uerrno) },
+#else
+    { MP_ROM_QSTR(MP_QSTR_uerrno), MP_ROM_PTR(&mp_module_uerrno) },
+#endif
 #endif
 #if MICROPY_PY_UCTYPES
     { MP_ROM_QSTR(MP_QSTR_uctypes), MP_ROM_PTR(&mp_module_uctypes) },
@@ -190,14 +197,20 @@ STATIC const mp_rom_map_elem_t mp_builtin_module_table[] = {
     { MP_ROM_QSTR(MP_QSTR_uzlib), MP_ROM_PTR(&mp_module_uzlib) },
 #endif
 #if MICROPY_PY_UJSON
+#if CIRCUITPY
 // CircuitPython: Defined in MICROPY_PORT_BUILTIN_MODULES, so not defined here.
 // TODO: move to shared-bindings/
-//    { MP_ROM_QSTR(MP_QSTR_ujson), MP_ROM_PTR(&mp_module_ujson) },
+#else
+    { MP_ROM_QSTR(MP_QSTR_ujson), MP_ROM_PTR(&mp_module_ujson) },
+#endif
 #endif
 #if MICROPY_PY_URE
+#if CIRCUITPY
 // CircuitPython: Defined in MICROPY_PORT_BUILTIN_MODULES, so not defined here.
 // TODO: move to shared-bindings/
-//    { MP_ROM_QSTR(MP_QSTR_ure), MP_ROM_PTR(&mp_module_ure) },
+#else
+    { MP_ROM_QSTR(MP_QSTR_ure), MP_ROM_PTR(&mp_module_ure) },
+#endif
 #endif
 #if MICROPY_PY_UHEAPQ
     { MP_ROM_QSTR(MP_QSTR_uheapq), MP_ROM_PTR(&mp_module_uheapq) },