diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index e3836b8..33f1873 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1202,7 +1202,8 @@
 {
     PyObject *m, *d, *v;
     const char *ext;
-    int set_file_name = 0, ret, len;
+    int set_file_name = 0, ret;
+    size_t len;
 
     m = PyImport_AddModule("__main__");
     if (m == NULL)