diff --git a/py/objexcept.c b/py/objexcept.c
index 7fd783b3a..de9bf1694 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -107,23 +107,23 @@ MP_DEFINE_EXCEPTION(Exception, BaseException)
     MP_DEFINE_EXCEPTION_BASE(NameError)
     MP_DEFINE_EXCEPTION(UnboundLocalError, NameError)
   MP_DEFINE_EXCEPTION(OSError, Exception)
+    MP_DEFINE_EXCEPTION_BASE(OSError)
     // Probably don't need these
-    /*MP_DEFINE_EXCEPTION_BASE(OSError)
-    MP_DEFINE_EXCEPTION(BlockingIOError, OSError)
+    /*MP_DEFINE_EXCEPTION(BlockingIOError, OSError)
     MP_DEFINE_EXCEPTION(ChildProcessError, OSError)
     MP_DEFINE_EXCEPTION(ConnectionError, OSError)
       MP_DEFINE_EXCEPTION(BrokenPipeError, ConnectionError)
       MP_DEFINE_EXCEPTION(ConnectionAbortedError, ConnectionError)
       MP_DEFINE_EXCEPTION(ConnectionRefusedError, ConnectionError)
       MP_DEFINE_EXCEPTION(ConnectionResetError, ConnectionError)
-    MP_DEFINE_EXCEPTION(FileExistsError, OSError)
-    MP_DEFINE_EXCEPTION(FileNotFoundError, OSError)
     MP_DEFINE_EXCEPTION(InterruptedError, OSError)
     MP_DEFINE_EXCEPTION(IsADirectoryError, OSError)
     MP_DEFINE_EXCEPTION(NotADirectoryError, OSError)
     MP_DEFINE_EXCEPTION(PermissionError, OSError)
     MP_DEFINE_EXCEPTION(ProcessLookupError, OSError)
     MP_DEFINE_EXCEPTION(TimeoutError, OSError)*/
+    MP_DEFINE_EXCEPTION(FileExistsError, OSError)
+    MP_DEFINE_EXCEPTION(FileNotFoundError, OSError)
   MP_DEFINE_EXCEPTION(ReferenceError, Exception)
   MP_DEFINE_EXCEPTION(RuntimeError, Exception)
     MP_DEFINE_EXCEPTION_BASE(RuntimeError)
@@ -137,6 +137,7 @@ MP_DEFINE_EXCEPTION(Exception, BaseException)
   MP_DEFINE_EXCEPTION(TypeError, Exception)
   MP_DEFINE_EXCEPTION(ValueError, Exception)
     //TODO: Implement UnicodeErrors which take arguments
+  /*
   MP_DEFINE_EXCEPTION(Warning, Exception)
     MP_DEFINE_EXCEPTION_BASE(Warning)
     MP_DEFINE_EXCEPTION(DeprecationWarning, Warning)
@@ -149,6 +150,7 @@ MP_DEFINE_EXCEPTION(Exception, BaseException)
     MP_DEFINE_EXCEPTION(UnicodeWarning, Warning)
     MP_DEFINE_EXCEPTION(BytesWarning, Warning)
     MP_DEFINE_EXCEPTION(ResourceWarning, Warning)
+    */
 
 mp_obj_t mp_obj_new_exception(const mp_obj_type_t *exc_type) {
     return mp_obj_new_exception_msg_varg(exc_type, NULL);
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index b30177acf..898e67582 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -37,56 +37,33 @@ Q(BaseException)
 Q(ArithmeticError)
 Q(AssertionError)
 Q(AttributeError)
-Q(BlockingIOError)
-Q(BrokenPipeError)
 Q(BufferError)
-Q(BytesWarning)
-Q(ChildProcessError)
-Q(ConnectionAbortedError)
-Q(ConnectionError)
-Q(ConnectionRefusedError)
-Q(ConnectionResetError)
-Q(DeprecationWarning)
 Q(EOFError)
 Q(EnvironmentError)
 Q(Exception)
 Q(FileExistsError)
 Q(FileNotFoundError)
 Q(FloatingPointError)
-Q(FutureWarning)
 Q(GeneratorExit)
 Q(IOError)
 Q(ImportError)
-Q(ImportWarning)
 Q(IndentationError)
 Q(IndexError)
-Q(InterruptedError)
-Q(IsADirectoryError)
 Q(KeyError)
 Q(LookupError)
 Q(MemoryError)
 Q(NameError)
-Q(NotADirectoryError)
 Q(NotImplementedError)
 Q(OSError)
 Q(OverflowError)
-Q(PendingDeprecationWarning)
-Q(PermissionError)
-Q(ProcessLookupError)
 Q(ReferenceError)
-Q(ResourceWarning)
 Q(RuntimeError)
-Q(RuntimeWarning)
 Q(SyntaxError)
-Q(SyntaxWarning)
 Q(SystemError)
 Q(SystemExit)
 Q(TabError)
-Q(TimeoutError)
 Q(TypeError)
 Q(UnboundLocalError)
-Q(UnicodeWarning)
-Q(UserWarning)
 Q(ValueError)
 Q(Warning)
 Q(ZeroDivisionError)
diff --git a/py/runtime.c b/py/runtime.c
index 03b662798..3a613eaf2 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -149,17 +149,13 @@ STATIC const mp_builtin_elem_t builtin_table[] = {
     { MP_QSTR_AssertionError, (mp_obj_t)&mp_type_AssertionError },
     { MP_QSTR_AttributeError, (mp_obj_t)&mp_type_AttributeError },
     { MP_QSTR_BufferError, (mp_obj_t)&mp_type_BufferError },
-    { MP_QSTR_BytesWarning, (mp_obj_t)&mp_type_BytesWarning },
-    { MP_QSTR_DeprecationWarning, (mp_obj_t)&mp_type_DeprecationWarning },
     { MP_QSTR_EOFError, (mp_obj_t)&mp_type_EOFError },
     { MP_QSTR_EnvironmentError, (mp_obj_t)&mp_type_EnvironmentError },
     { MP_QSTR_Exception, (mp_obj_t)&mp_type_Exception },
     { MP_QSTR_FloatingPointError, (mp_obj_t)&mp_type_FloatingPointError },
-    { MP_QSTR_FutureWarning, (mp_obj_t)&mp_type_FutureWarning },
     { MP_QSTR_GeneratorExit, (mp_obj_t)&mp_type_GeneratorExit },
     { MP_QSTR_IOError, (mp_obj_t)&mp_type_IOError },
     { MP_QSTR_ImportError, (mp_obj_t)&mp_type_ImportError },
-    { MP_QSTR_ImportWarning, (mp_obj_t)&mp_type_ImportWarning },
     { MP_QSTR_IndentationError, (mp_obj_t)&mp_type_IndentationError },
     { MP_QSTR_IndexError, (mp_obj_t)&mp_type_IndexError },
     { MP_QSTR_KeyError, (mp_obj_t)&mp_type_KeyError },
@@ -169,21 +165,15 @@ STATIC const mp_builtin_elem_t builtin_table[] = {
     { MP_QSTR_NotImplementedError, (mp_obj_t)&mp_type_NotImplementedError },
     { MP_QSTR_OSError, (mp_obj_t)&mp_type_OSError },
     { MP_QSTR_OverflowError, (mp_obj_t)&mp_type_OverflowError },
-    { MP_QSTR_PendingDeprecationWarning, (mp_obj_t)&mp_type_PendingDeprecationWarning },
     { MP_QSTR_ReferenceError, (mp_obj_t)&mp_type_ReferenceError },
-    { MP_QSTR_ResourceWarning, (mp_obj_t)&mp_type_ResourceWarning },
     { MP_QSTR_RuntimeError, (mp_obj_t)&mp_type_RuntimeError },
-    { MP_QSTR_RuntimeWarning, (mp_obj_t)&mp_type_RuntimeWarning },
     { MP_QSTR_SyntaxError, (mp_obj_t)&mp_type_SyntaxError },
-    { MP_QSTR_SyntaxWarning, (mp_obj_t)&mp_type_SyntaxWarning },
     { MP_QSTR_SystemError, (mp_obj_t)&mp_type_SystemError },
     { MP_QSTR_SystemExit, (mp_obj_t)&mp_type_SystemExit },
     { MP_QSTR_TabError, (mp_obj_t)&mp_type_TabError },
     { MP_QSTR_TypeError, (mp_obj_t)&mp_type_TypeError },
     { MP_QSTR_UnboundLocalError, (mp_obj_t)&mp_type_UnboundLocalError },
-    { MP_QSTR_UserWarning, (mp_obj_t)&mp_type_UserWarning },
     { MP_QSTR_ValueError, (mp_obj_t)&mp_type_ValueError },
-    { MP_QSTR_Warning, (mp_obj_t)&mp_type_Warning },
     { MP_QSTR_ZeroDivisionError, (mp_obj_t)&mp_type_ZeroDivisionError },
     { MP_QSTR_StopIteration, (mp_obj_t)&mp_type_StopIteration },
     // Somehow CPython managed to have OverflowError not inherit from ValueError ;-/