diff --git a/lang/mujs/Makefile b/lang/mujs/Makefile
index f2c98ebc281f..da03339e76a5 100644
--- a/lang/mujs/Makefile
+++ b/lang/mujs/Makefile
@@ -3,6 +3,7 @@
 PORTNAME=	mujs
 DISTVERSION=	1.0.6-6
 DISTVERSIONSUFFIX=	-g8c86834
+PORTREVISION=	1
 CATEGORIES=	lang devel
 
 PATCH_SITES=	https://github.com/${GH_ACCOUNT}/${PORTNAME}/commit/
@@ -31,6 +32,14 @@ PLIST_FILES=	bin/mujs \
 		lib/libmujs.a \
 		libdata/pkgconfig/mujs.pc
 
+OPTIONS_DEFINE=		32BIT
+OPTIONS_DEFAULT=	32BIT
+
+32BIT_DESC=		32-bit address space to allow for larger programs
+
+post-patch-32BIT-on:
+	@${REINPLACE_CMD} 's|typedef unsigned short js_Instruction|typedef int js_Instruction|' ${WRKSRC}/jsi.h
+
 post-install: # https://github.com/ccxvii/mujs/issues/99
 	@${STRIP_CMD} ${STAGEDIR}${PREFIX}/lib/libmujs.so