Add ImportError.
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index b246c5b..7efa85b 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -31,6 +31,7 @@
 
 Q(AssertionError)
 Q(AttributeError)
+Q(ImportError)
 Q(IndentationError)
 Q(IndexError)
 Q(KeyError)
diff --git a/py/runtime.c b/py/runtime.c
index 74c55ea..0f27273 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -92,6 +92,7 @@
 
     // built-in exceptions (TODO, make these proper classes, and const if possible)
     mp_map_add_qstr(&map_builtins, MP_QSTR_AttributeError, mp_obj_new_exception(MP_QSTR_AttributeError));
+    mp_map_add_qstr(&map_builtins, MP_QSTR_ImportError, mp_obj_new_exception(MP_QSTR_ImportError));
     mp_map_add_qstr(&map_builtins, MP_QSTR_IndexError, mp_obj_new_exception(MP_QSTR_IndexError));
     mp_map_add_qstr(&map_builtins, MP_QSTR_KeyError, mp_obj_new_exception(MP_QSTR_KeyError));
     mp_map_add_qstr(&map_builtins, MP_QSTR_NameError, mp_obj_new_exception(MP_QSTR_NameError));