diff --git a/dap/algos/radprof.py b/dap/algos/radprof.py
index 3229ed9..fd42d91 100644
--- a/dap/algos/radprof.py
+++ b/dap/algos/radprof.py
@@ -69,11 +69,11 @@ def calc_apply_threshold(results, data):
         if k not in results:
             return data
 
-    data = data.copy() # do the following in-place changes on a copy
-
     threshold_min = float(results["threshold_min"])
     threshold_max = float(results["threshold_max"])
 
+    data = data.copy() # do the following in-place changes on a copy
+
     threshold(data, threshold_min, threshold_max, np.nan)
 
     return data