diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index 9147bc2784313c70f1e54dc457da7466ba113577..39fa3cafb9fcf629a56a34da878e91e57b1ce289 100755
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -549,6 +549,9 @@ class Instrument:
         elif isinstance(fplan, str):
             logger.info("Using frequency-plan file '%s'", fplan)
             self.fplan_file = fplan
+            # Refuse to use a fplan file if no orbit files are used
+            if self.orbit_file is None:
+                raise ValueError("cannot use frequency-plan for non orbit files")
             # Without a standard lock config, there is no dataset
             # in the frequency-plan file and therefore we cannot use it
             if self.lock_config is None: