diff --git a/py/persistentcode.c b/py/persistentcode.c
index 78849fedff00835719130f137f7494b379a55084..ad502a5116623328b73104cf4836a42abd29aed6 100644
--- a/py/persistentcode.c
+++ b/py/persistentcode.c
@@ -41,7 +41,7 @@
 #define QSTR_LAST_STATIC MP_QSTR_zip
 
 // The current version of .mpy files
-#define MPY_VERSION (3)
+#define MPY_VERSION (4)
 
 // Macros to encode/decode flags to/from the feature byte
 #define MPY_FEATURE_ENCODE_FLAGS(flags) (flags)
diff --git a/tools/mpy-tool.py b/tools/mpy-tool.py
index 318343227c5dd949729220192a31d005b7b9e4d3..ff31a61bde8bb70c32456a8879124d7b6e3f0b61 100755
--- a/tools/mpy-tool.py
+++ b/tools/mpy-tool.py
@@ -57,7 +57,7 @@ class FreezeError(Exception):
         return 'error while freezing %s: %s' % (self.rawcode.source_file, self.msg)
 
 class Config:
-    MPY_VERSION = 3
+    MPY_VERSION = 4
     MICROPY_LONGINT_IMPL_NONE = 0
     MICROPY_LONGINT_IMPL_LONGLONG = 1
     MICROPY_LONGINT_IMPL_MPZ = 2