diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 5c9f5bca4d99..3aad6ef18504 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -63,19 +63,20 @@ static int proc_do_xprt(struct ctl_table *table, int write,
 			void *buffer, size_t *lenp, loff_t *ppos)
 {
 	char tmpbuf[256];
-	size_t len;
+	ssize_t len;
 
 	if (write || *ppos) {
 		*lenp = 0;
 		return 0;
 	}
 	len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
-	*lenp = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
+	len = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
 
-	if (*lenp < 0) {
+	if (len < 0) {
 		*lenp = 0;
 		return -EINVAL;
 	}
+	*lenp = len;
 	return 0;
 }