diff --git a/src/opm/output/eclipse/AggregateMSWData.cpp b/src/opm/output/eclipse/AggregateMSWData.cpp
index 68e315228..e07a33d39 100644
--- a/src/opm/output/eclipse/AggregateMSWData.cpp
+++ b/src/opm/output/eclipse/AggregateMSWData.cpp
@@ -180,30 +180,37 @@ namespace {
         return segmentOrder(segSet, 0);
     }
 
+    /// Accumulate connection flow rates (surface conditions) to their connecting segment.
     Opm::RestartIO::Helpers::SegmentSetSourceSinkTerms
-    getSegmentSetSSTerms(const std::string& wname, const Opm::WellSegments& segSet, const std::vector<Opm::data::Connection>& rateConns,
-                         const Opm::WellConnections& welConns, const Opm::UnitSystem& units)
+    getSegmentSetSSTerms(const Opm::WellSegments& segSet,
+                         const std::vector<Opm::data::Connection>& rateConns,
+                         const Opm::WellConnections& welConns,
+                         const Opm::UnitSystem& units)
     {
         std::vector<double> qosc (segSet.size(), 0.);
         std::vector<double> qwsc (segSet.size(), 0.);
         std::vector<double> qgsc (segSet.size(), 0.);
-        std::vector<const Opm::Connection* > openConnections;
-        using M  = ::Opm::UnitSystem::measure;
-        using R  = ::Opm::data::Rates::opt;
-        for (auto nConn = welConns.size(), connID = 0*nConn; connID < nConn; connID++) {
-            if (welConns[connID].state() == Opm::Connection::State::OPEN) openConnections.push_back(&welConns[connID]);
-        }
-        if (openConnections.size() != rateConns.size()) {
-            throw std::invalid_argument {
-                "Inconsistent number of open connections I in Opm::WellConnections (" +
-                std::to_string(welConns.size()) + ") and vector<Opm::data::Connection> (" +
-                std::to_string(rateConns.size()) + ") in Well " + wname
-            };
-        }
-        for (auto nConn = openConnections.size(), connID = 0*nConn; connID < nConn; connID++) {
-            const auto& segNo = openConnections[connID]->segment();
-            const auto& segInd = segSet.segmentNumberToIndex(segNo);
-            const auto& Q = rateConns[connID].rates;
+
+        using M = ::Opm::UnitSystem::measure;
+        using R = ::Opm::data::Rates::opt;
+
+        for (const auto& conn : welConns) {
+            if (conn.state() != Opm::Connection::State::OPEN) {
+                continue;
+            }
+
+            auto xcPos = std::find_if(rateConns.begin(), rateConns.end(),
+                [&conn](const Opm::data::Connection& xconn) -> bool
+            {
+                return xconn.index == conn.global_index();
+            });
+
+            if (xcPos == rateConns.end()) {
+                continue;
+            }
+
+            const auto segInd = segSet.segmentNumberToIndex(conn.segment());
+            const auto& Q = xcPos->rates;
 
             auto get = [&units, &Q](const M u, const R q) -> double
             {
@@ -225,15 +232,17 @@ namespace {
     }
 
     Opm::RestartIO::Helpers::SegmentSetFlowRates
-    getSegmentSetFlowRates(const std::string& wname, const Opm::WellSegments& segSet, const std::vector<Opm::data::Connection>& rateConns,
-                           const Opm::WellConnections& welConns, const Opm::UnitSystem& units)
+    getSegmentSetFlowRates(const Opm::WellSegments& segSet,
+                           const std::vector<Opm::data::Connection>& rateConns,
+                           const Opm::WellConnections& welConns,
+                           const Opm::UnitSystem& units)
     {
         std::vector<double> sofr (segSet.size(), 0.);
         std::vector<double> swfr (segSet.size(), 0.);
         std::vector<double> sgfr (segSet.size(), 0.);
         //
         //call function to calculate the individual segment source/sink terms
-        auto sSSST = getSegmentSetSSTerms(wname, segSet, rateConns, welConns, units);
+        auto segmentSources = getSegmentSetSSTerms(segSet, rateConns, welConns, units);
 
         // find an ordered list of segments
         auto orderedSegmentInd = segmentOrder(segSet);
@@ -244,9 +253,9 @@ namespace {
             const auto& segInd = sNFOSN[indOSN];
             // the segment flow rates is the sum of the the source/sink terms for each segment plus the flow rates from the inflow segments
             // add source sink terms
-            sofr[segInd] += sSSST.qosc[segInd];
-            swfr[segInd] += sSSST.qwsc[segInd];
-            sgfr[segInd] += sSSST.qgsc[segInd];
+            sofr[segInd] += segmentSources.qosc[segInd];
+            swfr[segInd] += segmentSources.qwsc[segInd];
+            sgfr[segInd] += segmentSources.qgsc[segInd];
             // add flow from all inflow segments
             for (const auto& segNo : segSet[segInd].inletSegments()) {
                 const auto & ifSegInd = segSet.segmentNumberToIndex(segNo);
@@ -255,6 +264,7 @@ namespace {
                 sgfr[segInd] += sgfr[ifSegInd];
             }
         }
+
         return {
             sofr,
             swfr,
@@ -655,7 +665,7 @@ namespace {
                 // find well connections and calculate segment rates based on well connection production/injection terms
                 auto sSFR = Opm::RestartIO::Helpers::SegmentSetFlowRates{};
                 if (haveWellRes) {
-                    sSFR = getSegmentSetFlowRates(well.name(), welSegSet, wRatesIt->second.connections, welConns, units);
+                    sSFR = getSegmentSetFlowRates(welSegSet, wRatesIt->second.connections, welConns, units);
                 }
 
                 std::string stringSegNum = std::to_string(segment0.segmentNumber());
diff --git a/tests/test_AggregateMSWData.cpp b/tests/test_AggregateMSWData.cpp
index b495febda..c94cad37b 100644
--- a/tests/test_AggregateMSWData.cpp
+++ b/tests/test_AggregateMSWData.cpp
@@ -551,6 +551,7 @@ END
 	    double qo = 5.;
 	    double qw = 4.;
 	    double qg = 50.;
+	    int firstConnectedCell = 90; // zero-based linear index of (1,5,2)
             for (int i = 0; i < 5; i++) {
 		xw["PROD"].connections.emplace_back();
 		auto& c = xw["PROD"].connections.back();
@@ -558,6 +559,8 @@ END
 		c.rates.set(o::wat, qw*(float(i)+1.))
                    .set(o::oil, qo*(float(i)+1.))
                    .set(o::gas, qg*(float(i)+1.));
+
+		c.index = firstConnectedCell + i;
 	    }
 	    auto seg = Opm::data::Segment{};
 	    for (std::size_t i = 1; i < 5; i++) {
@@ -569,6 +572,7 @@ END
 	    xw["WINJ"].rates.set(o::oil, 0.0);
 	    xw["WINJ"].rates.set(o::gas, 0.0);
 	    qw = 7.;
+	    firstConnectedCell = 409; // zero-based linear index of (10,1,9)
             for (int i = 0; i < 5; i++) {
 		xw["WINJ"].connections.emplace_back();
 		auto& c = xw["WINJ"].connections.back();
@@ -576,6 +580,8 @@ END
 		c.rates.set(o::wat, qw*(float(i)+1.))
 		       .set(o::oil, 0.)
 		       .set(o::gas, 0.);
+
+		c.index = firstConnectedCell - i;
 	    }
         }
         return xw;