diff --git a/build_ros2.sh b/build_ros2.sh
index 39a8b24..0a483f8 100644
--- a/build_ros2.sh
+++ b/build_ros2.sh
@@ -120,6 +120,35 @@ done
 VERSION=$(date +"%-y.%-m.%-d%H%M%S")
 echo "version=${VERSION}" > SAS_VERSION
 
+####################################################################
+#   libmarinholab-sas-core .deb (non-ROS C++ core, MarinhoLab/sas_cpp)
+#
+# The sas_core thin wrapper requires this .deb (find_package
+# marinholab_sas_core), so it must be built and installed before
+# colcon build below and before the ROS package .deb builds.
+# It is not a colcon package (no package.xml), so it cannot go
+# through the bloom loop below; it is built from its own
+# debian/ packaging (dpkg-buildflags-based CMake rules).
+#
+# The full clone (no --depth) lets sas_cpp's tools/version.sh count
+# commits since the monthly tag; tools/bump-changelog.sh (needs dch
+# from devscripts, see prebuild_ros2.sh) stamps debian/changelog with
+# that rolling YY.MM.NN version before dpkg-buildpackage.
+#
+# The .deb is written to tmp_ros2/ so the PPA extract step
+# (cp -f /root/tmp_ros2/*.deb) ships it together with the
+# ROS package .debs.
+####################################################################
+
+echo "Building libmarinholab-sas-core (sas_cpp @ ${SAS_CPP_REF:-main})"
+git clone --branch "${SAS_CPP_REF:-main}" \
+    https://github.com/MarinhoLab/sas_cpp.git
+cd sas_cpp
+bash tools/bump-changelog.sh
+dpkg-buildpackage -us -uc -b
+cd ..
+dpkg -i ./libmarinholab-sas-core_*.deb
+
 ####################################################################
 #                  Check with colcon first
 ####################################################################
diff --git a/prebuild_ros2.sh b/prebuild_ros2.sh
index becc1ab..3d3784f 100644
--- a/prebuild_ros2.sh
+++ b/prebuild_ros2.sh
@@ -7,6 +7,9 @@ sudo apt-get update -q
 sudo apt-get upgrade -y
 sudo apt-get autoremove -y
 sudo apt-get install -y dh-make dh-python python3-bloom
+# dch (devscripts): needed by sas_cpp's tools/bump-changelog.sh, which
+# stamps the rolling version into debian/changelog before dpkg-buildpackage
+sudo apt-get install -y devscripts
 
 # sas_robot_driver_gazebo
 sudo apt-get install libgz-transport13-dev