diff --git a/devel/gdb/Makefile b/devel/gdb/Makefile
--- a/devel/gdb/Makefile
+++ b/devel/gdb/Makefile
@@ -2,6 +2,7 @@
 
 PORTNAME=	gdb
 DISTVERSION=	11.1
+PORTREVISION=	1
 CATEGORIES=	devel
 MASTER_SITES=	GNU
 
diff --git a/devel/gdb/files/kgdb/fbsd-kvm.c b/devel/gdb/files/kgdb/fbsd-kvm.c
--- a/devel/gdb/files/kgdb/fbsd-kvm.c
+++ b/devel/gdb/files/kgdb/fbsd-kvm.c
@@ -144,6 +144,8 @@
 	} catch (const gdb_exception_error &e) {
 		return;
 	}
+	if (size == 0)
+		return;
 	rseq = MSGBUF_SEQ_TO_POS(size, rseq);
 	wseq = MSGBUF_SEQ_TO_POS(size, wseq);
 	if (rseq == wseq)