diff --git a/opm/common/OpmLog/StreamLog.cpp b/opm/common/OpmLog/StreamLog.cpp
index 6813cb4cb..556856ae8 100644
--- a/opm/common/OpmLog/StreamLog.cpp
+++ b/opm/common/OpmLog/StreamLog.cpp
@@ -22,9 +22,13 @@
 namespace Opm {
 
 
-StreamLog::StreamLog(const std::string& logFile , int64_t messageMask) : LogBackend(messageMask)
+StreamLog::StreamLog(const std::string& logFile , int64_t messageMask, bool append) : LogBackend(messageMask)
 {
-    m_ofstream.open( logFile.c_str() ,  std::ofstream::out );
+    if (append) {
+        m_ofstream.open( logFile.c_str() ,  std::ofstream::app );
+    } else {
+        m_ofstream.open( logFile.c_str() ,  std::ofstream::out );
+    }
     m_streamOwner = true;
     m_ostream = &m_ofstream;
 }
diff --git a/opm/common/OpmLog/StreamLog.hpp b/opm/common/OpmLog/StreamLog.hpp
index fc6c5467f..9e4048de4 100644
--- a/opm/common/OpmLog/StreamLog.hpp
+++ b/opm/common/OpmLog/StreamLog.hpp
@@ -31,7 +31,7 @@ namespace Opm {
 class StreamLog : public LogBackend {
 
 public:
-    StreamLog(const std::string& logFile , int64_t messageMask);
+    StreamLog(const std::string& logFile , int64_t messageMask, bool append = false);
     StreamLog(std::ostream& os , int64_t messageMask);
     virtual void addTaggedMessage(int64_t messageType, const std::string& messageTag, const std::string& message) override;
     ~StreamLog();