--- a/process/release.py
+++ b/process/release.py
@@ -2021,16 +2021,17 @@ def generateReleasePromotionBuilders(bra
             'category': category_name,
             'builddir': buildername,
             'slavebuilddir': normalizeName(buildername),
             'factory': partner_repack_factory,
             'properties': {
                 'branch': branch_name,
                 'platform': platform,
                 'product': product,
+                'basedir': normalizeName(buildername),
             }
         })
 
     # Don't merge release builder requests
     nomergeBuilders.update([b['name'] for b in builders])
 
     # Make sure builders have the right properties
     addBuilderProperties(builders)