diff --git a/lib/ssh.c b/lib/ssh.c
index a6d379f79..dc8ee8b8e 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -455,7 +455,7 @@ static int sshkeycallback(CURL *easy,
 #ifdef HAVE_LIBSSH2_SFTP_SEEK64
 #define SFTP_SEEK(x,y) libssh2_sftp_seek64(x, (libssh2_uint64_t)y)
 #else
-#define SFTP_SEEK(x,y) libssh2_sftp_seek(x, y)
+#define SFTP_SEEK(x,y) libssh2_sftp_seek(x, (size_t)y)
 #endif
 
 /*