diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 384399d..a15f2d9 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -891,7 +891,8 @@
 {
     uLong adler32val = adler32(0L, Z_NULL, 0);
     Byte *buf;
-    int len, signed_val;
+    int len;
+    long signed_val;
 
     if (!PyArg_ParseTuple(args, "s#|k:adler32", &buf, &len, &adler32val))
 	return NULL;
@@ -914,7 +915,8 @@
 {
     uLong crc32val = crc32(0L, Z_NULL, 0);
     Byte *buf;
-    int len, signed_val;
+    int len;
+    long signed_val;
 
     if (!PyArg_ParseTuple(args, "s#|k:crc32", &buf, &len, &crc32val))
 	return NULL;