diff --git a/meta/classes-recipe/rootfs-postcommands.bbclass b/meta/classes-recipe/rootfs-postcommands.bbclass
index e81b69a239..920da94ba2 100644
--- a/meta/classes-recipe/rootfs-postcommands.bbclass
+++ b/meta/classes-recipe/rootfs-postcommands.bbclass
@@ -206,7 +206,9 @@ read_only_rootfs_hook () {
 		# Also tweak the key location for dropbear in the same way.
 		if [ -d ${IMAGE_ROOTFS}/etc/dropbear ]; then
 			if [ ! -e ${IMAGE_ROOTFS}/etc/dropbear/dropbear_rsa_host_key ]; then
-				echo "DROPBEAR_RSAKEY_DIR=/var/lib/dropbear" >> ${IMAGE_ROOTFS}/etc/default/dropbear
+				if ! grep -q "^DROPBEAR_RSAKEY_DIR=" ${IMAGE_ROOTFS}/etc/default/dropbear ; then
+					echo "DROPBEAR_RSAKEY_DIR=/var/lib/dropbear" >> ${IMAGE_ROOTFS}/etc/default/dropbear
+				fi
 			fi
 		fi
 	fi