diff --git a/graphics/diplib/Makefile b/graphics/diplib/Makefile
index 2c4c9d31dfaf..7853e5d54076 100644
--- a/graphics/diplib/Makefile
+++ b/graphics/diplib/Makefile
@@ -1,28 +1,31 @@
 PORTNAME=	diplib
 DISTVERSION=	3.4.2
 CATEGORIES=	graphics
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Library and development environment for quantitative image analysis
 WWW=		https://diplib.org/
 
 LICENSE=	APACHE20
 LICENSE_FILE=	${WRKSRC}/LICENSE.txt
 
 BROKEN_aarch64=	runaway builds, see https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=276690
 
 LIB_DEPENDS=	libglfw.so:graphics/glfw
 
 USES=		cmake:testing compiler:c++14-lang gl
 USE_GL=		gl glut
 USE_LDCONFIG=	yes
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	DIPlib
 
 CXXFLAGS_powerpc64=	-mvsx
 CMAKE_OFF=	DIP_BUILD_PYDIP
 CMAKE_TESTING_ON=	DIP_ENABLE_DOCTEST
 CMAKE_TESTING_TARGET=	check # one test fails, see https://github.com/DIPlib/diplib/issues/120
 
+CFLAGS_i386=	-msse2 # fix build failure: error: always_inline function '_mm_setzero_si128' requires target feature 'sse2', but would be inlined into function 'defilter_sub4' that is compiled without support for 'sse2'
+CXXFLAGS_i386=	-msse2
+
 .include <bsd.port.mk>