diff --git a/Include/pyport.h b/Include/pyport.h
index 9b5c54d..e0d9b7d 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -99,6 +99,8 @@
 
 /* Largest positive value of type Py_ssize_t. */
 #define PY_SSIZE_T_MAX ((Py_ssize_t)(((size_t)-1)>>1))
+/* Smallest positive value of type Py_ssize_t. */
+#define PY_SSIZE_T_MIN (-PY_SSIZE_T_MAX-1)
 
 /* PY_FORMAT_SIZE_T is a platform-specific modifier for use in a printf
  * format to convert an argument with the width of a size_t or Py_ssize_t.