diff --git lang/spidermonkey78/Makefile lang/spidermonkey78/Makefile
index 02d576a0e9e6..1605d6277e39 100644
--- lang/spidermonkey78/Makefile
+++ lang/spidermonkey78/Makefile
@@ -13,7 +13,7 @@ COMMENT=	Standalone JavaScript based from Mozilla 78-esr
 LICENSE=	MPL20
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
-BUILD_DEPENDS=	${LOCALBASE}/bin/clang${LLVM_DEFAULT}:devel/llvm${LLVM_DEFAULT} \
+BUILD_DEPENDS=	${LOCALBASE}/bin/clang++90:devel/llvm90 \
 		${LOCALBASE}/bin/python${PYTHON3_DEFAULT}:lang/python${PYTHON3_DEFAULT:S/.//g} \
 		${RUST_DEFAULT}>=1.35:lang/${RUST_DEFAULT} \
 		autoconf-2.13:devel/autoconf213 \
@@ -22,7 +22,7 @@ LIB_DEPENDS=	libffi.so:devel/libffi \
 		libicudata.so:devel/icu \
 		libnspr4.so:devel/nspr
 
-USES=		compiler gmake localbase pathfix pkgconfig python:build \
+USES=		compiler:c++17-lang gmake localbase pathfix pkgconfig python:build \
 		readline tar:xz
 USE_LDCONFIG=	yes
 SP_VER=		78
@@ -51,8 +51,8 @@ CONFIGURE_ARGS=	--disable-debug \
 CONFIGURE_ENV=	HOST_CC=${CC} \
 		HOST_CXX=${CXX}
 
-CONFIGURE_ENV+=	LLVM_CONFIG=llvm-config${LLVM_DEFAULT} \
-		LLVM_OBJDUMP=llvm-objdump${LLVM_DEFAULT}
+CONFIGURE_ENV+=	LLVM_CONFIG=llvm-config90 \
+		LLVM_OBJDUMP=llvm-objdump90
 
 BINARY_ALIAS=	python3=${PYTHON_CMD}
 PLIST_SUB=	SP_VER=${SP_VER}
@@ -67,10 +67,10 @@ CONFIGURE_TARGET=	x86_64-portbld-freebsd${OSREL}
 .if ${CHOSEN_COMPILER_TYPE} == gcc
 USE_GCC=	yes
 .elif ${CC} == cc && ${CXX} == c++ && exists(/usr/lib/libc++.so)
-CPP=		${LOCALBASE}/bin/clang-cpp${LLVM_DEFAULT}
-CC=		${LOCALBASE}/bin/clang${LLVM_DEFAULT}
-CXX=		${LOCALBASE}/bin/clang++${LLVM_DEFAULT}
-BUILD_DEPENDS+=	${LOCALBASE}/bin/clang${LLVM_DEFAULT}:devel/llvm${LLVM_DEFAULT}
+CPP=		${LOCALBASE}/bin/clang-cpp90
+CC=		${LOCALBASE}/bin/clang90
+CXX=		${LOCALBASE}/bin/clang++90
+BUILD_DEPENDS+=	${LOCALBASE}/bin/clang90:devel/llvm90
 .endif
 
 post-patch: