diff --git a/src/combinecases.cpp b/src/combinecases.cpp
index 60aafa0ea..4526afd7d 100644
--- a/src/combinecases.cpp
+++ b/src/combinecases.cpp
@@ -262,7 +262,9 @@ void CombineCasesDialog::OnEvt(wxCommandEvent& e)
 							analysis_period_this = current_case->Values(0).Get("c_lifetime")->Value();
 						}
 						else if (financial_name != "None") {
+							bool use_lifetime = current_case->Values(0).Get("system_use_lifetime_output")->Boolean();
 							analysis_period_this = current_case->Values(0).Get("analysis_period")->Value();
+							analysis_period_this = use_lifetime ? analysis_period_this : 1;
 						}
 
 						// determine hourly generation profile of current case