diff --git a/src/eap_peer/eap_fast_pac.c b/src/eap_peer/eap_fast_pac.c
index 541cce50d..403728808 100644
--- a/src/eap_peer/eap_fast_pac.c
+++ b/src/eap_peer/eap_fast_pac.c
@@ -497,6 +497,7 @@ static void eap_fast_write(char **buf, char **pos, size_t *buf_len,
 			*buf = NULL;
 			return;
 		}
+		*pos = nbuf + (*pos - *buf);
 		*buf = nbuf;
 		*buf_len += need;
 	}