diff --git a/src/ML-POD/fitpod_command.h b/src/ML-POD/fitpod_command.h
index d632a8e074..e0928c8df3 100644
--- a/src/ML-POD/fitpod_command.h
+++ b/src/ML-POD/fitpod_command.h
@@ -67,7 +67,7 @@ class FitPOD : public Command {
 
     double fitting_weights[12] = {100.0, 1.0, 0.0, 1, 1, 0, 0, 1, 1, 1, 1, 1e-10};
 
-    void copydatainfo(datastruct &data)
+    void copydatainfo(datastruct &data) const
     {
       data.data_path = data_path;
       data.file_format = file_format;