diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index f957e2c..223afac 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -790,7 +790,8 @@
                                               slicelen);
         else {
             char *result_buf = (char *)PyMem_Malloc(slicelen);
-            Py_ssize_t cur, i;
+            size_t cur;
+            Py_ssize_t i;
             PyObject *result;
 
             if (result_buf == NULL)
@@ -910,7 +911,8 @@
             memcpy(self->data + start, vbuf.buf, slicelen);
         }
         else {
-            Py_ssize_t cur, i;
+            size_t cur;
+            Py_ssize_t i;
 
             for (cur = start, i = 0;
                  i < slicelen;