diff --git a/lib/decompress.c b/lib/decompress.c
index 86069d74..37f3c78 100644
--- a/lib/decompress.c
+++ b/lib/decompress.c
@@ -54,7 +54,7 @@
 	{ {0, 0}, NULL, NULL }
 };
 
-decompress_fn __init decompress_method(const unsigned char *inbuf, int len,
+decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
 				const char **name)
 {
 	const struct compress_format *cf;