diff --git a/misc/otter/Makefile b/misc/otter/Makefile
index fbdb221138d4..2e00b210bea7 100644
--- a/misc/otter/Makefile
+++ b/misc/otter/Makefile
@@ -3,13 +3,16 @@
 
 PORTNAME=	otter
 PORTVERSION=	3.3f
-PORTREVISION=	3
+PORTREVISION=	4
 CATEGORIES=	misc
 MASTER_SITES=	http://www-unix.mcs.anl.gov/AR/otter/dist33/
 
 MAINTAINER=	wollman@FreeBSD.org
 COMMENT=	Theorem prover and finite model searcher
 
+LICENSE=	PD
+LICENSE_FILE=	${WRKSRC}/Legal
+
 USES=		shebangfix
 SHEBANG_FILES=	examples-mace2/Perl-examples/commute4_filter