diff --git a/build_library/base_image_util.sh b/build_library/base_image_util.sh
index 5b26bed20e..be72ffb3b8 100755
--- a/build_library/base_image_util.sh
+++ b/build_library/base_image_util.sh
@@ -60,8 +60,10 @@ create_base_image() {
   # Zero all fs free space to make it more compressible so auto-update
   # payloads become smaller, not fatal since it won't work on linux < 3.2
   sudo fstrim "${root_fs_dir}" || true
-  if [[ -d "${root_fs_dir}/media/state" ]]; then
-      sudo fstrim "${root_fs_dir}/media/state" || true
+  if [[ "${disk_layout}" == *-usr ]]; then
+    sudo fstrim "${root_fs_dir}/usr" || true
+  else
+    sudo fstrim "${root_fs_dir}/media/state" || true
   fi
 
   cleanup_mounts "${root_fs_dir}"
diff --git a/build_library/dev_image_util.sh b/build_library/dev_image_util.sh
index 50d6ed491f..4b3d965d0a 100755
--- a/build_library/dev_image_util.sh
+++ b/build_library/dev_image_util.sh
@@ -36,10 +36,22 @@ install_dev_packages() {
   sudo mkdir -p "${root_fs_dir}/root"
   sudo touch "${root_fs_dir}/root/.dev_mode"
 
+  # Remount the system partition read-write by default.
+  # The remount services are provided by coreos-base/coreos-init
+  local fs_wants="${root_fs_dir}/usr/lib/systemd/system/local-fs.target.wants"
+  sudo mkdir -p "${fs_wants}"
+  if [[ "${disk_layout}" == *-usr ]]; then
+    sudo ln -s ../remount-usr.service "${fs_wants}"
+  else
+    sudo ln -s ../remount-root.service "${fs_wants}"
+  fi
+
   # Zero all fs free space, not fatal since it won't work on linux < 3.2
   sudo fstrim "${root_fs_dir}" || true
-  if [[ -d "${root_fs_dir}/media/state" ]]; then
-      sudo fstrim "${root_fs_dir}/media/state" || true
+  if [[ "${disk_layout}" == *-usr ]]; then
+    sudo fstrim "${root_fs_dir}/usr" || true
+  else
+    sudo fstrim "${root_fs_dir}/media/state" || true
   fi
 
   info "Developer image built and stored at ${image_name}"