diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index a65f3beec..5a0a3a338 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -762,8 +762,6 @@ STATIC const mp_rom_map_elem_t mp_module_builtins_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_ViperTypeError), MP_ROM_PTR(&mp_type_ViperTypeError) },
     #endif
     { MP_ROM_QSTR(MP_QSTR_ZeroDivisionError), MP_ROM_PTR(&mp_type_ZeroDivisionError) },
-    // Somehow CPython managed to have OverflowError not inherit from ValueError ;-/
-    // TODO: For MICROPY_CPYTHON_COMPAT==0 use ValueError to avoid exc proliferation
 
     // Extra builtins as defined by a port
     MICROPY_PORT_BUILTINS
diff --git a/py/objexcept.c b/py/objexcept.c
index dadbe98ae..869a80bbe 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -241,10 +241,8 @@ MP_DEFINE_EXCEPTION(Exception, BaseException)
   MP_DEFINE_EXCEPTION(AssertionError, Exception)
   MP_DEFINE_EXCEPTION(AttributeError, Exception)
   //MP_DEFINE_EXCEPTION(BufferError, Exception)
-  //MP_DEFINE_EXCEPTION(EnvironmentError, Exception) use OSError instead
   MP_DEFINE_EXCEPTION(EOFError, Exception)
   MP_DEFINE_EXCEPTION(ImportError, Exception)
-  //MP_DEFINE_EXCEPTION(IOError, Exception) use OSError instead
   MP_DEFINE_EXCEPTION(LookupError, Exception)
     MP_DEFINE_EXCEPTION(IndexError, LookupError)
     MP_DEFINE_EXCEPTION(KeyError, LookupError)