diff --git a/science/ncrystal/Makefile b/science/ncrystal/Makefile
index 19025f36c9da..03ad5e4f38dd 100644
--- a/science/ncrystal/Makefile
+++ b/science/ncrystal/Makefile
@@ -1,27 +1,33 @@
 PORTNAME=	ncrystal
 DISTVERSIONPREFIX=	v
 DISTVERSION=	4.4.4
 CATEGORIES=	science # physics
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Library for thermal neutron transport in crystals and other materials
 WWW=		https://github.com/mctools/ncrystal
 
 LICENSE=	APACHE20
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
+# ncrystal-4.4.4/ncrystal_core/src/core/NCDefs.cc:25:18: error:
+# static assertion failed due to requirement 'std::numeric_limits<unsigned int>::max() >=
+# std::numeric_limits<unsigned long long>::max()': NCrystal is no longer supported on 32bit systems
+NOT_FOR_ARCHS=	armv7 i386 powerpc
+NOT_FOR_ARCHS_REASON=	NCrystal is no longer supported on 32bit systems
+
 USES=		cmake:testing python:build,test shebangfix
 USE_LDCONFIG=	yes
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	mctools
 
 SHEBANG_FILES=	tests/scripts/* \
 		tests/cmake/mctools_testlauncher.py
 
 CMAKE_TESTING_ON=	NCRYSTAL_ENABLE_TESTING \
 			NCRYSTAL_ENABLE_CORE_TEST
 
 # tests as of 4.4.4: 99% tests passed, 1 tests failed out of 129, see https://github.com/mctools/ncrystal/issues/355
 
 .include <bsd.port.mk>