diff --git a/math/octave-forge-joystick/Makefile b/math/octave-forge-joystick/Makefile
index 75c192b70a09..1469177b1b74 100644
--- a/math/octave-forge-joystick/Makefile
+++ b/math/octave-forge-joystick/Makefile
@@ -1,26 +1,26 @@
 PORTNAME=	octave-forge-joystick
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.0.4
 CATEGORIES=	math
 
 MAINTAINER=	stephen@FreeBSD.org
 COMMENT=	Octave-forge package ${OCTAVE_PKGNAME}
 WWW=		https://packages.octave.org/
 
 LICENSE=	GPLv3
 LICENSE_FILE=	${WRKDIR}/${OCTAVE_SRC}/COPYING
 
-BUILD_DEPENDS+	cmake:devel/cmake # Required by configure.
+BUILD_DEPENDS+=	cmake:devel/cmake # Required by configure.
 
 LIB_DEPENDS+=	libSDL2.so:devel/sdl20
 
 USES=		octave autoreconf
 USE_GITHUB=	yes
 GH_ACCOUNT=	gnu-octave
 GH_PROJECT=	octave-joystick
 
 GNU_CONFIGURE=	yes
 
 OCTAVE_SRC=	${GH_PROJECT}-${DISTVERSION}
 
 .include <bsd.port.mk>