diff --git a/meta/recipes-support/boost/boost.inc b/meta/recipes-support/boost/boost.inc
index 7a343e54f6..3cd71c4d6e 100644
--- a/meta/recipes-support/boost/boost.inc
+++ b/meta/recipes-support/boost/boost.inc
@@ -203,6 +203,17 @@ do_install() {
 		--libdir=${D}${libdir} \
 		--includedir=${D}${includedir} \
 		install
+
+	# In 1.91 boost-system became a header-only "modular" library and is no
+	# longer selectable through --with-system, so it is not part of BOOST_LIBS
+	# and the top-level install target no longer ships its CMake package
+	# config. Install that modular target explicitly so downstream
+	# find_package(Boost COMPONENTS system) keeps working.
+	b2 ${BJAM_OPTS} \
+		--libdir=${D}${libdir} \
+		--includedir=${D}${includedir} \
+		libs/system//install
+
 	for lib in ${BOOST_LIBS}; do
 		if [ -e ${D}${libdir}/libboost_${lib}.a ]; then
 			ln -s libboost_${lib}.a ${D}${libdir}/libboost_${lib}-mt.a