diff --git a/setup.py b/setup.py
index 7f863a4..9ddf2e9 100644
--- a/setup.py
+++ b/setup.py
@@ -1897,7 +1897,7 @@
 
     def _decimal_ext(self):
         extra_compile_args = []
-        undef_macros = ['NDEBUG']
+        undef_macros = []
         if '--with-system-libmpdec' in sysconfig.get_config_var("CONFIG_ARGS"):
             include_dirs = []
             libraries = ['mpdec']