diff --git a/lib/galaxy/tools/parameters/basic.py b/lib/galaxy/tools/parameters/basic.py
index 613fad22e517..1a5f31678725 100644
--- a/lib/galaxy/tools/parameters/basic.py
+++ b/lib/galaxy/tools/parameters/basic.py
@@ -1150,7 +1150,7 @@ def _get_dbkey_names( self, trans=None ):
         if not self.tool:
             # Hack for unit tests, since we have no tool
             return util.read_dbnames( None )
-        return trans.app.genome_builds.get_genome_build_names( trans=trans )
+        return self.tool.app.genome_builds.get_genome_build_names( trans=trans )
 
 
 class ColumnListParameter( SelectToolParameter ):