diff --git a/saqc/funcs/harm_functions.py b/saqc/funcs/harm_functions.py
index 360f9ff0a1461af116f5660f3fbfd0a228dc12cb..32f0f696b1bd785614c68f434fd75fec1056accc 100644
--- a/saqc/funcs/harm_functions.py
+++ b/saqc/funcs/harm_functions.py
@@ -74,6 +74,9 @@ def harmWrapper(heap={}):
         # now we can manipulate it without loosing information gathered before harmonization
         dat_col, flagger_merged_clean, _ = _outsortCrap(dat_col, field, flagger_merged, drop_flags=drop_flags)
 
+        if dat_col.empty:
+            return data, flagger
+
         # interpolation! (yeah)
         dat_col, chunk_bounds = _interpolateGrid(
             dat_col,