diff --git a/src/kiss.c b/src/kiss.c
index ce2373b..ed5fadf 100644
--- a/src/kiss.c
+++ b/src/kiss.c
@@ -136,7 +136,7 @@ ssize_t patty_kiss_tnc_recv(patty_kiss_tnc *tnc,
 
         c = ((uint8_t *)tnc->buf)[tnc->offset++];
 
-        if (tnc->offset == tnc->bufsz) {
+        if (tnc->offset == tnc->readlen) {
             tnc->offset = 0;
         }