diff --git a/Mac/mwerks/mwerks_nonshared_config.h b/Mac/mwerks/mwerks_nonshared_config.h
index b492384..fd7f15d 100644
--- a/Mac/mwerks/mwerks_nonshared_config.h
+++ b/Mac/mwerks/mwerks_nonshared_config.h
@@ -18,3 +18,4 @@
 #define MAC_TCL			/* This *must* be on if USE_TK is on */
 /* #define USE_MAC_SHARED_LIBRARY	/* Enable code to add shared-library resources */
 /* #define USE_MAC_APPLET_SUPPORT	/* Enable code to run a PYC resource */
+/* #define USE_MALLOC_DEBUG			/* Enable range checking and other malloc debugging */
diff --git a/Mac/mwerks/mwerks_shared_config.h b/Mac/mwerks/mwerks_shared_config.h
index 5bcdeae..8d6db02 100644
--- a/Mac/mwerks/mwerks_shared_config.h
+++ b/Mac/mwerks/mwerks_shared_config.h
@@ -19,3 +19,4 @@
 /* #define MAC_TCL		/* This *must* be on if USE_TK is on */
 #define USE_MAC_SHARED_LIBRARY		/* Enable code to add shared-library resources */
 #define USE_MAC_APPLET_SUPPORT		/* Enable code to run a PYC resource */
+/* #define USE_MALLOC_DEBUG			/* Enable range checking and other malloc debugging */
diff --git a/Mac/mwerks/mwerks_small_config.h b/Mac/mwerks/mwerks_small_config.h
index 5e5e33a..aa3c791 100644
--- a/Mac/mwerks/mwerks_small_config.h
+++ b/Mac/mwerks/mwerks_small_config.h
@@ -18,3 +18,4 @@
 /* #define MAC_TCL			/* This *must* be on if USE_TK is on */
 /* #define USE_MAC_SHARED_LIBRARY	/* Enable code to add shared-library resources */
 /* #define USE_MAC_APPLET_SUPPORT	/* Enable code to run a PYC resource */
+/* #define USE_MALLOC_DEBUG			/* Enable range checking and other malloc debugging */