diff --git a/scripts/wsrep_sst_common.sh b/scripts/wsrep_sst_common.sh
index 73a026b4edc..2bd1579e0d8 100644
--- a/scripts/wsrep_sst_common.sh
+++ b/scripts/wsrep_sst_common.sh
@@ -193,7 +193,7 @@ case "$1" in
               if [ -z "$original_cmd" ]; then
                   original_cmd="$1"
               else
-                  original_cmd+=" $1"
+                  original_cmd="$original_cmd $1"
               fi
            fi
            shift