diff --git a/ebos/damariswriter.hh b/ebos/damariswriter.hh
index 791aa3405..e8eeaa36f 100644
--- a/ebos/damariswriter.hh
+++ b/ebos/damariswriter.hh
@@ -44,6 +44,7 @@
 
 #include <opm/simulators/utils/DeferredLoggingErrorHelpers.hpp>
 #include <opm/simulators/utils/ParallelRestart.hpp>
+#include <opm/simulators/flow/countGlobalCells.hpp>
 
 #include <opm/common/OpmLog/OpmLog.hpp>
 
@@ -516,7 +517,7 @@ private:
         }
 
         const auto& gridView = simulator_.vanguard().gridView();
-        const int num_interior = Opm::detail::
+        const int num_interior = detail::
             countLocalInteriorCellsGridView(gridView);
         const bool log = this->collectToIORank_.isIORank();
 
diff --git a/ebos/eclgenericoutputblackoilmodule.cc b/ebos/eclgenericoutputblackoilmodule.cc
index f2b3184bd..74cc960e8 100644
--- a/ebos/eclgenericoutputblackoilmodule.cc
+++ b/ebos/eclgenericoutputblackoilmodule.cc
@@ -711,7 +711,7 @@ regionSum(const ScalarBuffer& property,
         // the property does not contain the ghostcells
         // This code assumes that that the ghostcells are
         // added after the interior cells
-        // Is this a valid assumption?
+        // OwnerCellsFirst = True
         assert(regionId.size() >= property.size());
         for (std::size_t j = 0; j < property.size(); ++j) {
             const int regionIdx = regionId[j] - 1;
diff --git a/ebos/ecloutputblackoilmodule.hh b/ebos/ecloutputblackoilmodule.hh
index 595230c4a..29c6dcf04 100644
--- a/ebos/ecloutputblackoilmodule.hh
+++ b/ebos/ecloutputblackoilmodule.hh
@@ -173,6 +173,14 @@ public:
 
         this->forceDisableFipresvOutput_ =
             EWOMS_GET_PARAM(TypeTag, bool, ForceDisableResvFluidInPlaceOutput);
+
+        if (! EWOMS_GET_PARAM(TypeTag, bool, OwnerCellsFirst)) {
+            const std::string msg = "The output code does not support --owner-cells-first=false.";
+            if (collectToIORank.isIORank()) {
+                OpmLog::error(msg);
+            }
+            OPM_THROW_NOLOG(std::runtime_error, msg);
+        }
     }
 
     /*!
diff --git a/ebos/eclwriter.hh b/ebos/eclwriter.hh
index 1d335f71c..ff3afcd47 100644
--- a/ebos/eclwriter.hh
+++ b/ebos/eclwriter.hh
@@ -331,7 +331,7 @@ public:
         }
 
         const auto& gridView = simulator_.vanguard().gridView();
-        const int num_interior = Opm::detail::
+        const int num_interior = detail::
             countLocalInteriorCellsGridView(gridView);
 
         this->eclOutputModule_->
@@ -562,7 +562,7 @@ private:
         const auto& gridView = simulator_.vanguard().gridView();
         const bool log = this->collectToIORank_.isIORank();
 
-        const int num_interior = Opm::detail::
+        const int num_interior = detail::
             countLocalInteriorCellsGridView(gridView);
         this->eclOutputModule_->
             allocBuffers(num_interior, reportStepNum,