diff --git a/graphics/opennurbs/Makefile b/graphics/opennurbs/Makefile
index c5f231107406..55c7b3b58f3a 100644
--- a/graphics/opennurbs/Makefile
+++ b/graphics/opennurbs/Makefile
@@ -1,50 +1,44 @@
 PORTNAME=	opennurbs
 PORTVERSION=	8.32.26160.13001
 DISTVERSIONPREFIX=	v
 PORTEPOCH=	1
 CATEGORIES=	graphics
 
 MAINTAINER=	fernape@FreeBSD.org
 COMMENT=	Tools to accurately transfer 3-D geometry between applications
 WWW=		http://opennurbs.org/
 
 LICENSE=	ZLIB
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	mcneel
 
 LIB_DEPENDS=	libuuid.so:misc/libuuid
 
 USES=		cmake compiler:c++17-lang iconv:build localbase
 CFLAGS+=	-DON_COMPILER_CLANG	\
 		-DON_SIZEOF_WCHAR_T=4
 USE_LDCONFIG=	yes
 
 OPTIONS_DEFINE=	EXAMPLES
 
 .include <bsd.port.pre.mk>
 
-.if ${ARCH} != "sparc64" && ${ARCH} != "powerpc" && ${ARCH} != powerpc64
-CFLAGS+=	-DON_LITTLE_ENDIAN
-.else
-CFLAGS+=	-DON_BIG_ENDIAN
-.endif
-
 do-install-EXAMPLES-on:
 	@${MKDIR} ${STAGEDIR}${EXAMPLESDIR}
 	${INSTALL_DATA} ${WRKSRC}/examples_linking_pragmas.h \
 		${STAGEDIR}${EXAMPLESDIR}
 	${INSTALL_DATA} ${WRKSRC}/opennurbs.h ${STAGEDIR}${EXAMPLESDIR}
 .for i in brep convert gl read roundtrip test userdata write
 	@${MKDIR} ${STAGEDIR}${EXAMPLESDIR}/example_${i}
 	cd ${WRKSRC}/example_${i} && ${COPYTREE_SHARE} . ${STAGEDIR}${EXAMPLESDIR}/example_${i} "-name *\.cpp -or -name *\.h"
 .endfor
 
 post-install:
 	${INSTALL_DATA} ${WRKSRC}/opennurbs_cpp_base.h ${STAGEDIR}${PREFIX}/include/OpenNURBS/
 	${MV} ${STAGEDIR}${PREFIX}/lib/libOpenNURBS.so ${STAGEDIR}${PREFIX}/lib/libOpenNURBS.so.0
 	${LN} -sf libOpenNURBS.so.0 ${STAGEDIR}${PREFIX}/lib/libOpenNURBS.so
 	${RM} ${STAGEDIR}${PREFIX}/lib/libzlib.a
 
 .include <bsd.port.post.mk>
diff --git a/graphics/opennurbs/files/patch-opennurbs__system__runtime.h b/graphics/opennurbs/files/patch-opennurbs__system__runtime.h
new file mode 100644
index 000000000000..a7519f4b05fc
--- /dev/null
+++ b/graphics/opennurbs/files/patch-opennurbs__system__runtime.h
@@ -0,0 +1,20 @@
+--- opennurbs_system_runtime.h.orig	2026-06-25 07:56:15 UTC
++++ opennurbs_system_runtime.h
+@@ -177,9 +177,16 @@
+ /* Attempt to determing runtime pointer size */
+ #if (defined(_M_X64) || defined(__LP64__) || defined(__ppc64__))
+ #define ON_64BIT_RUNTIME
+-#elif (defined(_M_X86) || defined(__LP32__))
++#elif (defined(_M_X86) || defined(__LP32__) || defined(__ILP32__))
+ #define ON_32BIT_RUNTIME
+ #endif
++#endif
++
++/* Attempt to determine byte order */
++#if defined(__BIG_ENDIAN__)
++#define ON_BIG_ENDIAN
++#elif defined(__LITTLE_ENDIAN__)
++#define ON_LITTLE_ENDIAN
+ #endif
+ 
+ #if defined(ON_64BIT_RUNTIME) && defined(ON_32BIT_RUNTIME)