diff --git a/modules/motus/downloaddb/main.nf b/modules/motus/downloaddb/main.nf
index e2a0cec6..58f3cd03 100644
--- a/modules/motus/downloaddb/main.nf
+++ b/modules/motus/downloaddb/main.nf
@@ -18,7 +18,7 @@ process MOTUS_DOWNLOADDB {
 
     script:
     def args     = task.ext.args ?: ''
-    def software = ${motus_downloaddb.simpleName}_copy.py
+    def software = "${motus_downloaddb.simpleName}_copy.py"
     """
     ## must copy script file to working directory,
     ## otherwise the reference_db will be download to bin folder