diff --git a/ports/esp8266/mpconfigport.h b/ports/esp8266/mpconfigport.h
index 37a794f44b2f..18b2e47e29dc 100644
--- a/ports/esp8266/mpconfigport.h
+++ b/ports/esp8266/mpconfigport.h
@@ -19,7 +19,6 @@
 #define MICROPY_OPT_MATH_FACTORIAL              (0)
 #define MICROPY_REPL_EMACS_KEYS                 (0)
 #define MICROPY_PY_BUILTINS_COMPLEX             (0)
-#define MICROPY_MODULE_ATTR_DELEGATION          (0)
 #define MICROPY_PY_FUNCTION_ATTRS               (0)
 #define MICROPY_PY_DELATTR_SETATTR              (0)
 #define MICROPY_PY_BUILTINS_STR_CENTER          (0)
diff --git a/py/modsys.c b/py/modsys.c
index a0ecb87b5f30..72817ce00935 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -195,7 +195,21 @@ STATIC mp_obj_t mp_sys_settrace(mp_obj_t obj) {
 MP_DEFINE_CONST_FUN_OBJ_1(mp_sys_settrace_obj, mp_sys_settrace);
 #endif // MICROPY_PY_SYS_SETTRACE
 
+
+#if MICROPY_PY_SYS_PS1_PS2 && !MICROPY_PY_SYS_ATTR_DELEGATION
+#error "MICROPY_PY_SYS_PS1_PS2 requires MICROPY_PY_SYS_ATTR_DELEGATION"
+#endif
+
+#if MICROPY_PY_SYS_TRACEBACKLIMIT && !MICROPY_PY_SYS_ATTR_DELEGATION
+#error "MICROPY_PY_SYS_TRACEBACKLIMIT requires MICROPY_PY_SYS_ATTR_DELEGATION"
+#endif
+
+#if MICROPY_PY_SYS_ATTR_DELEGATION && !MICROPY_MODULE_ATTR_DELEGATION
+#error "MICROPY_PY_SYS_ATTR_DELEGATION requires MICROPY_MODULE_ATTR_DELEGATION"
+#endif
+
 #if MICROPY_PY_SYS_ATTR_DELEGATION
+// Must be kept in sync with the enum at the top of mpstate.h.
 STATIC const uint16_t sys_mutable_keys[] = {
     #if MICROPY_PY_SYS_PS1_PS2
     MP_QSTR_ps1,
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 504ad64b0126..b6f8838662d8 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -842,7 +842,7 @@ typedef double mp_float_t;
 // Whether modules can use MP_REGISTER_MODULE_DELEGATION() to delegate failed
 // attribute lookups to a custom handler function.
 #ifndef MICROPY_MODULE_ATTR_DELEGATION
-#define MICROPY_MODULE_ATTR_DELEGATION (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
+#define MICROPY_MODULE_ATTR_DELEGATION (MICROPY_PY_SYS_ATTR_DELEGATION || MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
 #endif
 
 // Whether to call __init__ when importing builtin modules for the first time.
diff --git a/py/mpstate.h b/py/mpstate.h
index 80b49cb6b645..3786131de6b4 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -40,6 +40,8 @@
 // memory system, runtime and virtual machine.  The state is a global
 // variable, but in the future it is hoped that the state can become local.
 
+#if MICROPY_PY_SYS_ATTR_DELEGATION
+// Must be kept in sync with sys_mutable_keys in modsys.c.
 enum {
     #if MICROPY_PY_SYS_PS1_PS2
     MP_SYS_MUTABLE_PS1,
@@ -50,6 +52,7 @@ enum {
     #endif
     MP_SYS_MUTABLE_NUM,
 };
+#endif // MICROPY_PY_SYS_ATTR_DELEGATION
 
 // This structure contains dynamic configuration for the compiler.
 #if MICROPY_DYNAMIC_COMPILER