diff --git a/src/cal_tools/gotthard2/gotthard2lib.py b/src/cal_tools/gotthard2/gotthard2lib.py
index f828f35418c80b0168d1cdc8cc10563f3e9a38e3..86f8ac6e865348f3f3c9d7cd0fe91cffc1276b85 100644
--- a/src/cal_tools/gotthard2/gotthard2lib.py
+++ b/src/cal_tools/gotthard2/gotthard2lib.py
@@ -7,7 +7,7 @@ import extra_data
 
 def map_da_to_source(dc, das, source_template, karabo_id, affixes):
     source_names = [
-        f"{source_template.format(karabo_id=karabo_id, input_source_affixes=aff)}"  # noqa
+        source_template.format(karabo_id=karabo_id, input_source_affixes=aff)  # noqa
         for aff in affixes
     ]
     if len(source_names) != len(das):