diff --git a/build_image b/build_image
index 14637906bd..1250996185 100755
--- a/build_image
+++ b/build_image
@@ -322,14 +322,14 @@ make_image_bootable() {
   if [[ "${ARCH}" == "arm" ]]; then
     # TODO(wad) mmcblk1p3 is hardcoded for arm for now!
     usb_disk="/dev/mmcblk1p3"
-    kernel_part="--kernel_cmdline='"
-    kernel_part="${kernel_part}\
-$(cat ${OUTPUT_DIR}/boot.config | tr -s '\n' ' ')"
-    kernel_part="${kernel_part} ${FLAGS_arm_extra_bootargs}'"
+    kernel_part="--kernel_cmdline=\"${FLAGS_arm_extra_bootargs}\" "
+    # TODO(wad) Integrate dmtable extraction into the arm build
+    # E.g.  $(cat ${OUTPUT_DIR}/boot.config | tr -s '\n' ' ')"
     local kpart_offset="--kernel_partition_offset=${koffset}"
-    local kpart_size="\
-      --kernel_partition_sectors=$(partsize ${OUTPUT_DIR}/${image_name} 2)"
+    local kpart_size="--kernel_partition_sectors="
+    kpart_size="${kpart_size}$(partsize ${OUTPUT_DIR}/${image_name} 2)"
     kernel_part="${kernel_part} ${kpart_size} ${kpart_offset}"
+    info "Using addition bootloader arguments: ${kernel_part}"
     bootloader_to="${OUTPUT_DIR}/arm.mbr"
   fi
 
diff --git a/update_bootloaders.sh b/update_bootloaders.sh
index 8919559a8f..5b216b7c56 100755
--- a/update_bootloaders.sh
+++ b/update_bootloaders.sh
@@ -54,7 +54,10 @@ if ! type -p update_x86_bootloaders; then
     local template_dir="$4"
 
     # Pull out the dm="" values
-    dm_table=$(echo "$kernel_cmdline" | sed -s 's/.*dm="\([^"]*\)".*/\1/')
+    dm_table=
+    if echo "$kernel_cmdline" | grep -q 'dm="'; then
+      dm_table=$(echo "$kernel_cmdline" | sed -s 's/.*dm="\([^"]*\)".*/\1/')
+    fi
 
     # Rewrite grub table
     grub_dm_table_a=${dm_table//${old_root}/\$linuxpartA}
@@ -177,7 +180,10 @@ elif [[ "${FLAGS_arch}" = "arm" ]]; then
     info "Extracting the kernel command line from ${FLAGS_kernel_partition}"
     kernel_cfg=$(dump_kernel_config "${kernel_partition}")
   fi
-  dm_table=$(echo "$kernel_cfg" | sed -s 's/.*dm="\([^"]*\)".*/\1/')
+  dm_table=
+  if echo "$kernel_cfg" | grep -q 'dm="'; then
+    dm_table=$(echo "$kernel_cfg" | sed -s 's/.*dm="\([^"]*\)".*/\1/')
+  fi
   # TODO(wad) assume usb_disk contains the arm boot location for now.
   new_root="${FLAGS_usb_disk}"
   info "Replacing dm slave devices with /dev/${new_root}"
@@ -194,7 +200,7 @@ elif [[ "${FLAGS_arch}" = "arm" ]]; then
     ${device} \
     "'dm=\"${dm_table}\"'")
   sudo dd bs=1 count=`stat --printf="%s" ${MBR_SCRIPT_UIMG}` \
-     if="$MBR_SCRIPT_UIMG" of=${FLAGS_to} conv=notrunc
+     if="$MBR_SCRIPT_UIMG" of=${FLAGS_to}
   info "Emitted new ARM MBR to ${FLAGS_to}"
 fi