diff --git a/scripts/build-docker-base.sh b/scripts/build-docker-base.sh
index 307c9e6..2bf0440 100755
--- a/scripts/build-docker-base.sh
+++ b/scripts/build-docker-base.sh
@@ -30,8 +30,12 @@ if [[ -z "$BUILD_BRANCH_FOR_IMAGE_TAG" ]] ; then
     BUILD_BRANCH_FOR_IMAGE_TAG="${BUILD_BRANCH/#r\//rc-}"
 fi
 
-base_image_tag="${BUILD_BRANCH_FOR_IMAGE_TAG=}-${BUILD_STREAM}-$TIMESTAMP"
-base_image_latest_tag="${BUILD_BRANCH_FOR_IMAGE_TAG=}-${BUILD_STREAM}-latest"
+if [[ -z "$BASE_IMAGE_TAG_PREFIX" ]] ; then
+    BASE_IMAGE_TAG_PREFIX="$BUILD_BRANCH_FOR_IMAGE_TAG"
+fi
+
+base_image_tag="${BASE_IMAGE_TAG_PREFIX}-${BUILD_STREAM}-$TIMESTAMP"
+base_image_latest_tag="${BASE_IMAGE_TAG_PREFIX}-${BUILD_STREAM}-latest"
 
 declare -a cmd=(
     "./build-stx-base.sh"
diff --git a/scripts/build-docker-images.sh b/scripts/build-docker-images.sh
index 2c4d553..0a89f2b 100755
--- a/scripts/build-docker-images.sh
+++ b/scripts/build-docker-images.sh
@@ -30,6 +30,10 @@ if [[ -z "$BUILD_BRANCH_FOR_IMAGE_TAG" ]] ; then
     BUILD_BRANCH_FOR_IMAGE_TAG="${BUILD_BRANCH/#r\//rc-}"
 fi
 
+if [[ -z "$BASE_IMAGE_TAG_PREFIX" ]] ; then
+    BASE_IMAGE_TAG_PREFIX="$BUILD_BRANCH_FOR_IMAGE_TAG"
+fi
+
 HOST_WORKSPACE="$BUILD_HOME/workspace"
 
 wheels_file="std/build-wheels-$DOCKER_BASE_OS-$BUILD_STREAM/stx-$DOCKER_BASE_OS-$BUILD_STREAM-wheels.tar"
@@ -52,7 +56,7 @@ declare -a cmd=(
 if [[ -n "$DOCKER_IMAGE_BASE" ]] ; then
     cmd+=("--base=$DOCKER_IMAGE_BASE")
 elif $BUILD_DOCKER_BASE_IMAGE ; then
-    base_image_tag="${BUILD_BRANCH_FOR_IMAGE_TAG}-${BUILD_STREAM}-$TIMESTAMP"
+    base_image_tag="${BASE_IMAGE_TAG_PREFIX}-${BUILD_STREAM}-$TIMESTAMP"
     docker_base_image="$DOCKER_REGISTRY_ORG/stx-$DOCKER_BASE_OS:$base_image_tag"
     if [[ -n "$DOCKER_REGISTRY" ]] ; then
         docker_base_image="$DOCKER_REGISTRY/$docker_base_image"
diff --git a/scripts/templates/build.conf.example.in b/scripts/templates/build.conf.example.in
index a4c7236..037b222 100644
--- a/scripts/templates/build.conf.example.in
+++ b/scripts/templates/build.conf.example.in
@@ -26,6 +26,13 @@ BUILD_BRANCH="master"
 # rc-stx.8.0
 BUILD_BRANCH_FOR_IMAGE_TAG="${BUILD_BRANCH/#r\//rc-}"
 
+# Prefix for the base image tag, ie: stx-debian:PREFIX-stable-TIMESTAMP
+# This applies only to the base image, ie stx-debian
+# Example for openstack builds:
+#   master-openstack => stx-debian:master-openstack-debian-TIMESTAMP
+# If empty we will use BUILD_BRANCH_FOR_IMAGE_TAG.
+BASE_IMAGE_TAG_PREFIX=
+
 # Project name, must be unique for a given BUILD_USER
 PROJECT_ID="dpanech-debian"