diff --git a/data/helpers.d/filesystem b/data/helpers.d/filesystem
index 6836aeebe..d8e7dc4c7 100644
--- a/data/helpers.d/filesystem
+++ b/data/helpers.d/filesystem
@@ -46,7 +46,15 @@ ynh_backup() {
     local SRC_PATH="$1"
     local DEST_PATH="${2:-}"
     local IS_BIG="${3:-0}"
+    BACKUP_CORE_ONLY=${BACKUP_CORE_ONLY:-0}
 
+    # If backing up core only (used by ynh_backup_before_upgrade),
+    # don't backup big data items
+    if [ "$IS_BIG" == "1" ] && [ "$BACKUP_CORE_ONLY" == "1" ] ; then
+      echo "$SRC_PATH will not be saved, because backup_core_only is set." >&2
+      return 0
+    fi
+    
     # ==============================================================================
     # Format correctly source and destination paths
     # ==============================================================================
diff --git a/data/helpers.d/utils b/data/helpers.d/utils
index 288ac393c..cc057eb0b 100644
--- a/data/helpers.d/utils
+++ b/data/helpers.d/utils
@@ -77,7 +77,7 @@ ynh_backup_before_upgrade () {
 	fi
 
 	# Create backup
-	sudo yunohost backup create --ignore-system --apps $app --name $app_bck-pre-upgrade$backup_number --verbose
+	sudo BACKUP_CORE_ONLY=1 yunohost backup create --ignore-system --apps $app --name $app_bck-pre-upgrade$backup_number --verbose
 	if [ "$?" -eq 0 ]
 	then
 		# If the backup succeeded, remove the previous backup