diff --git a/ApplicationLibCode/ReservoirDataModel/RigCaseCellResultsData.cpp b/ApplicationLibCode/ReservoirDataModel/RigCaseCellResultsData.cpp
index b4f00c813b..c61ba6b9e7 100644
--- a/ApplicationLibCode/ReservoirDataModel/RigCaseCellResultsData.cpp
+++ b/ApplicationLibCode/ReservoirDataModel/RigCaseCellResultsData.cpp
@@ -3364,8 +3364,12 @@ void RigCaseCellResultsData::copyResultsMetaDataFromMainCase( RigEclipseCaseData
                                                               RiaDefines::PorosityModelType poroModel,
                                                               std::vector<RimEclipseCase*>  destinationCases )
 {
-    std::vector<RigEclipseResultAddress> resAddresses  = mainCaseResultsData->results( poroModel )->existingResults();
-    std::vector<RigEclipseTimeStepInfo>  timeStepInfos = mainCaseResultsData->results( poroModel )->timeStepInfos( resAddresses[0] );
+    std::vector<RigEclipseResultAddress> resAddresses = mainCaseResultsData->results( poroModel )->existingResults();
+    std::vector<RigEclipseTimeStepInfo>  timeStepInfos;
+    if ( !resAddresses.empty() )
+    {
+        timeStepInfos = mainCaseResultsData->results( poroModel )->timeStepInfos( resAddresses[0] );
+    }
 
     const std::vector<RigEclipseResultInfo> resultInfos = mainCaseResultsData->results( poroModel )->infoForEachResultIndex();
 
diff --git a/ApplicationLibCode/UnitTests/CMakeLists.txt b/ApplicationLibCode/UnitTests/CMakeLists.txt
index 25dd04e2f6..d705e2bad9 100644
--- a/ApplicationLibCode/UnitTests/CMakeLists.txt
+++ b/ApplicationLibCode/UnitTests/CMakeLists.txt
@@ -22,6 +22,7 @@ set(SOURCE_UNITTEST_FILES
     ${CMAKE_CURRENT_LIST_DIR}/RifReaderOpmCommon-Test.cpp
     ${CMAKE_CURRENT_LIST_DIR}/RifReaderEclipseSummary-Test.cpp
     ${CMAKE_CURRENT_LIST_DIR}/RigActiveCellInfo-Test.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/RigCaseCellResultsData-Test.cpp
     ${CMAKE_CURRENT_LIST_DIR}/RigEclipseCaseDataTools-Test.cpp
     ${CMAKE_CURRENT_LIST_DIR}/RigEclipseCrossPlotDataExtractor-Test.cpp
     ${CMAKE_CURRENT_LIST_DIR}/RigEclipseResultTools-Test.cpp
diff --git a/ApplicationLibCode/UnitTests/RigCaseCellResultsData-Test.cpp b/ApplicationLibCode/UnitTests/RigCaseCellResultsData-Test.cpp
new file mode 100644
index 0000000000..50290106e1
--- /dev/null
+++ b/ApplicationLibCode/UnitTests/RigCaseCellResultsData-Test.cpp
@@ -0,0 +1,41 @@
+/////////////////////////////////////////////////////////////////////////////////
+//
+//  Copyright (C) 2026 Equinor ASA
+//
+//  ResInsight is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
+//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+//  FITNESS FOR A PARTICULAR PURPOSE.
+//
+//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
+//  for more details.
+//
+/////////////////////////////////////////////////////////////////////////////////
+
+#include "gtest/gtest.h"
+
+#include "RimEclipseResultCase.h"
+
+#include "RigCaseCellResultsData.h"
+#include "RigEclipseCaseData.h"
+#include "RigEclipseResultAddress.h"
+
+#include <memory>
+
+//--------------------------------------------------------------------------------------------------
+/// A main case without any results must not be indexed for its first result.
+//--------------------------------------------------------------------------------------------------
+TEST( RigCaseCellResultsData, CopyResultsMetaDataFromMainCaseWithoutResults )
+{
+    std::unique_ptr<RimEclipseResultCase> resultCase( new RimEclipseResultCase );
+    cvf::ref<RigEclipseCaseData>          eclipseCase = new RigEclipseCaseData( resultCase.get() );
+
+    const auto poroModel = RiaDefines::PorosityModelType::MATRIX_MODEL;
+    ASSERT_TRUE( eclipseCase->results( poroModel )->existingResults().empty() );
+
+    RigCaseCellResultsData::copyResultsMetaDataFromMainCase( eclipseCase.p(), poroModel, {} );
+}