diff --git a/saqc/funcs/curvefit.py b/saqc/funcs/curvefit.py
index cef464e858dbccd9f4860ee5ad50c92776eff95e..8e61688de925098716cb42a47155336d67d7cf5f 100644
--- a/saqc/funcs/curvefit.py
+++ b/saqc/funcs/curvefit.py
@@ -190,7 +190,7 @@ def fitPolynomial(data: DictOfSeries, field: str, flagger: BaseFlagger,
                 )
 
     if return_residues:
-        residues = residues - to_fit
+        residues = to_fit - residues
 
     data[field] = residues
     if eval_flags: