diff --git a/ComputingTasks.cc b/ComputingTasks.cc
index 134ea288..50922be8 100644
--- a/ComputingTasks.cc
+++ b/ComputingTasks.cc
@@ -1727,7 +1727,7 @@ EstimationDataStatement::writeOutput(ostream &output, const string &basename) co
 {
   options_list.writeOutput(output, "options_.dataset");
   if (options_list.date_options.find("first_obs") == options_list.date_options.end())
-    output << "options_.dataset.firstobs = options_.initial_period;" << endl;
+    output << "options_.dataset.first_obs = options_.initial_period;" << endl;
 }
 
 SubsamplesStatement::SubsamplesStatement(const string &name1_arg,