diff --git a/opm/simulators/wells/BlackoilWellModelGeneric.cpp b/opm/simulators/wells/BlackoilWellModelGeneric.cpp
index 232a2cde4..fff177200 100644
--- a/opm/simulators/wells/BlackoilWellModelGeneric.cpp
+++ b/opm/simulators/wells/BlackoilWellModelGeneric.cpp
@@ -293,7 +293,9 @@ initializeWellPerfData()
                 checker.connectionFound(connection_index);
                 if (connection.state() != Connection::State::SHUT) {
                     OPM_THROW(std::runtime_error,
-                              "Connection state: " << Connection::State2String(connection.state()) << " not handled");
+                              "Connection state: " +
+                              Connection::State2String(connection.state()) +
+                              " not handled");
                 }
             }
             // Note: we rely on the connections being filtered! I.e. there are only connections