diff --git a/Mac/mwerks/mwerks_carbon_config.h b/Mac/mwerks/mwerks_carbon_config.h
index 491cf63bd8d..bebdfe1d4ad 100644
--- a/Mac/mwerks/mwerks_carbon_config.h
+++ b/Mac/mwerks/mwerks_carbon_config.h
@@ -42,3 +42,6 @@
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_carbonplugin_config.h b/Mac/mwerks/mwerks_carbonplugin_config.h
index de94aa8f3b4..6a10716dcce 100644
--- a/Mac/mwerks/mwerks_carbonplugin_config.h
+++ b/Mac/mwerks/mwerks_carbonplugin_config.h
@@ -18,3 +18,6 @@
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_nonshared_config.h b/Mac/mwerks/mwerks_nonshared_config.h
index fd4f09322a7..64f9a482251 100644
--- a/Mac/mwerks/mwerks_nonshared_config.h
+++ b/Mac/mwerks/mwerks_nonshared_config.h
@@ -43,3 +43,6 @@
 #include <stdio.h>
 extern int fileno(FILE *);
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_nscarbon_config.h b/Mac/mwerks/mwerks_nscarbon_config.h
index de3af4531c0..58a5a9b7fe2 100644
--- a/Mac/mwerks/mwerks_nscarbon_config.h
+++ b/Mac/mwerks/mwerks_nscarbon_config.h
@@ -47,3 +47,6 @@
 #include <stdio.h>
 extern int fileno(FILE *);
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_plugin_config.h b/Mac/mwerks/mwerks_plugin_config.h
index 9aa494188e7..1413f44980f 100644
--- a/Mac/mwerks/mwerks_plugin_config.h
+++ b/Mac/mwerks/mwerks_plugin_config.h
@@ -15,3 +15,6 @@
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_shared_config.h b/Mac/mwerks/mwerks_shared_config.h
index 279ea128ec9..414bedf0305 100644
--- a/Mac/mwerks/mwerks_shared_config.h
+++ b/Mac/mwerks/mwerks_shared_config.h
@@ -45,3 +45,6 @@
 #include <stdio.h>
 extern int fileno(FILE *);
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_shcarbon_config.h b/Mac/mwerks/mwerks_shcarbon_config.h
index bf7fbe687e3..a9d3916e2a8 100644
--- a/Mac/mwerks/mwerks_shcarbon_config.h
+++ b/Mac/mwerks/mwerks_shcarbon_config.h
@@ -49,3 +49,6 @@
 #include <stdio.h>
 extern int fileno(FILE *);
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_small_config.h b/Mac/mwerks/mwerks_small_config.h
index d3087f7f8ce..6d08f1bd671 100644
--- a/Mac/mwerks/mwerks_small_config.h
+++ b/Mac/mwerks/mwerks_small_config.h
@@ -42,3 +42,6 @@
 #include <stdio.h>
 extern int fileno(FILE *);
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_thrcarbonsm_config.h b/Mac/mwerks/mwerks_thrcarbonsm_config.h
index 05fda979332..e52c373f32d 100644
--- a/Mac/mwerks/mwerks_thrcarbonsm_config.h
+++ b/Mac/mwerks/mwerks_thrcarbonsm_config.h
@@ -42,3 +42,6 @@
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_threadsmall_config.h b/Mac/mwerks/mwerks_threadsmall_config.h
index 0a64cad14f9..83c8a3e5bd5 100644
--- a/Mac/mwerks/mwerks_threadsmall_config.h
+++ b/Mac/mwerks/mwerks_threadsmall_config.h
@@ -37,3 +37,6 @@
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif
diff --git a/Mac/mwerks/mwerks_tkplugin_config.h b/Mac/mwerks/mwerks_tkplugin_config.h
index d0fb8112a9a..aef32fbb5eb 100644
--- a/Mac/mwerks/mwerks_tkplugin_config.h
+++ b/Mac/mwerks/mwerks_tkplugin_config.h
@@ -11,3 +11,6 @@
 #define USE_TK			/* Include _tkinter module in core Python */
 #define MAC_TCL			/* This *must* be on if USE_TK is on */
 #define WITHOUT_FRAMEWORKS	/* Use old-style Universal Header includes, not Carbon/Carbon.h */
+#ifndef Py_DEBUG
+#define NDEBUG
+#endif