diff --git a/py/builtintables.c b/py/builtintables.c
index 7b35207fa552f51b3c39e16b9725607a5c38a0b7..5712a3ef568356c6f88ea884b788bff440f6322d 100644
--- a/py/builtintables.c
+++ b/py/builtintables.c
@@ -123,7 +123,6 @@ STATIC const mp_map_elem_t mp_builtin_object_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_EOFError), (mp_obj_t)&mp_type_EOFError },
     { MP_OBJ_NEW_QSTR(MP_QSTR_Exception), (mp_obj_t)&mp_type_Exception },
     { MP_OBJ_NEW_QSTR(MP_QSTR_GeneratorExit), (mp_obj_t)&mp_type_GeneratorExit },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_IOError), (mp_obj_t)&mp_type_IOError },
     { MP_OBJ_NEW_QSTR(MP_QSTR_ImportError), (mp_obj_t)&mp_type_ImportError },
     { MP_OBJ_NEW_QSTR(MP_QSTR_IndentationError), (mp_obj_t)&mp_type_IndentationError },
     { MP_OBJ_NEW_QSTR(MP_QSTR_IndexError), (mp_obj_t)&mp_type_IndexError },
diff --git a/py/obj.h b/py/obj.h
index d96e4ec751b6cbe77ce510e1411e93863e22e146..0156286818b0addff7a37f227f41913490ab7afd 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -326,7 +326,6 @@ extern const mp_obj_type_t mp_type_AttributeError;
 extern const mp_obj_type_t mp_type_EOFError;
 extern const mp_obj_type_t mp_type_Exception;
 extern const mp_obj_type_t mp_type_GeneratorExit;
-extern const mp_obj_type_t mp_type_IOError;
 extern const mp_obj_type_t mp_type_ImportError;
 extern const mp_obj_type_t mp_type_IndentationError;
 extern const mp_obj_type_t mp_type_IndexError;
diff --git a/py/objexcept.c b/py/objexcept.c
index 7f0736543a63ff2a0d136dfee67f4a5854c8a9b1..9b22acd995cf90d068f22a3ec6f0e0490a0c37a7 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -224,10 +224,10 @@ 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)
+  //MP_DEFINE_EXCEPTION(EnvironmentError, Exception) use OSError instead
   MP_DEFINE_EXCEPTION(EOFError, Exception)
   MP_DEFINE_EXCEPTION(ImportError, Exception)
-  MP_DEFINE_EXCEPTION(IOError, Exception)
+  //MP_DEFINE_EXCEPTION(IOError, Exception) use OSError instead
   MP_DEFINE_EXCEPTION(LookupError, Exception)
     MP_DEFINE_EXCEPTION_BASE(LookupError)
     MP_DEFINE_EXCEPTION(IndexError, LookupError)
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index fda140f11f4b865e181e8341417e364a9d44f892..6a63f0780b93170a85577bf3f354fb32774d2e84 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -105,7 +105,6 @@ Q(FileExistsError)
 Q(FileNotFoundError)
 Q(FloatingPointError)
 Q(GeneratorExit)
-Q(IOError)
 Q(ImportError)
 Q(IndentationError)
 Q(IndexError)
diff --git a/stmhal/modselect.c b/stmhal/modselect.c
index a84c94554c6c2475ef41854efa72d1ad0314ee17..ff9df8f5ec5c35f2b1f57f35667830dce704fc9d 100644
--- a/stmhal/modselect.c
+++ b/stmhal/modselect.c
@@ -26,6 +26,7 @@
 
 #include <stdint.h>
 #include <stdio.h>
+#include <errno.h>
 
 #include "stm32f4xx_hal.h"
 
@@ -213,7 +214,7 @@ STATIC mp_obj_t poll_modify(mp_obj_t self_in, mp_obj_t obj_in, mp_obj_t eventmas
     mp_obj_poll_t *self = self_in;
     mp_map_elem_t *elem = mp_map_lookup(&self->poll_map, mp_obj_id(obj_in), MP_MAP_LOOKUP);
     if (elem == NULL) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_IOError, "object was never registered"));
+        nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(ENOENT)));
     }
     ((poll_obj_t*)elem->value)->flags = mp_obj_get_int(eventmask_in);
     return mp_const_none;
diff --git a/tests/basics/exceptpoly.py b/tests/basics/exceptpoly.py
index 599a72b2a2d9602316ee68dab8e3fee091c35441..2dc68c13b578f95a4ea5db3e101055b27d3f40b6 100644
--- a/tests/basics/exceptpoly.py
+++ b/tests/basics/exceptpoly.py
@@ -108,15 +108,15 @@ except Exception:
 #except FutureWarning:
 #    print("Caught FutureWarning")
 
-try:
-    raise IOError
-except Exception:
-    print("Caught IOError via Exception")
+#try:
+#    raise IOError
+#except Exception:
+#    print("Caught IOError via Exception")
 
-try:
-    raise IOError
-except IOError:
-    print("Caught IOError")
+#try:
+#    raise IOError
+#except IOError:
+#    print("Caught IOError")
 
 try:
     raise ImportError