diff --git a/py/mpconfig.h b/py/mpconfig.h
index 17c5a770c4..44095bd10b 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -4,6 +4,20 @@
 
 #include <mpconfigport.h>
 
+#ifndef INT_FMT
+// printf format spec to use for machine_int_t and friends
+#ifdef __LP64__
+// Archs where machine_int_t == long, long != int
+#define UINT_FMT "%lu"
+#define INT_FMT "%ld"
+#else
+// Archs where machine_int_t == int
+#define UINT_FMT "%u"
+#define INT_FMT "%d"
+#endif
+#endif //INT_FMT
+
+
 // Any options not explicitly set in mpconfigport.h will get default
 // values below.
 
diff --git a/unix-cpy/mpconfigport.h b/unix-cpy/mpconfigport.h
index db72b31455..983b166a55 100644
--- a/unix-cpy/mpconfigport.h
+++ b/unix-cpy/mpconfigport.h
@@ -11,15 +11,11 @@
 #ifdef __LP64__
 typedef long machine_int_t; // must be pointer size
 typedef unsigned long machine_uint_t; // must be pointer size
-#define UINT_FMT "%lu"
-#define INT_FMT "%ld"
 #else
 // These are definitions for machines where sizeof(int) == sizeof(void*),
 // regardless for actual size.
 typedef int machine_int_t; // must be pointer size
 typedef unsigned int machine_uint_t; // must be pointer size
-#define UINT_FMT "%u"
-#define INT_FMT "%d"
 #endif
 
 #define BYTES_PER_WORD sizeof(machine_int_t)
diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index 3d0dc8a567..36cf138c17 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -11,15 +11,11 @@
 #ifdef __LP64__
 typedef long machine_int_t; // must be pointer size
 typedef unsigned long machine_uint_t; // must be pointer size
-#define UINT_FMT "%lu"
-#define INT_FMT "%ld"
 #else
 // These are definitions for machines where sizeof(int) == sizeof(void*),
 // regardless for actual size.
 typedef int machine_int_t; // must be pointer size
 typedef unsigned int machine_uint_t; // must be pointer size
-#define UINT_FMT "%u"
-#define INT_FMT "%d"
 #endif
 
 #define BYTES_PER_WORD sizeof(machine_int_t)