diff --git a/data-access/engine/src/vlkb-obscore/src/database/SqlSchema_INSERT.cpp b/data-access/engine/src/vlkb-obscore/src/database/SqlSchema_INSERT.cpp
index eddf0a08c3a098c74ff32915785a0dd432ddf4ac..80e25754b237df03d5afc58f513ee211d8e44ec3 100644
--- a/data-access/engine/src/vlkb-obscore/src/database/SqlSchema_INSERT.cpp
+++ b/data-access/engine/src/vlkb-obscore/src/database/SqlSchema_INSERT.cpp
@@ -316,7 +316,7 @@ void SqlSchema_INSERT::appendRow(
       {
          const double SPEED_OF_LIGHT{299792458};// [m/s]
          double val{SPEED_OF_LIGHT / rest_frequency};
-         obscoreRow[em_min] = to_string(val); //get_wavelen(EM_PRECISION, hdu.key_values);
+         obscoreRow[em_min] = (rest_frequency==0.0) ? "NULL" : to_string(val); //get_wavelen(EM_PRECISION, hdu.key_values);
       }
       catch(const std::exception&  ex)
       {