diff --git a/opm/models/utils/parametersystem.cpp b/opm/models/utils/parametersystem.cpp
index 920ca5711..fecd600cc 100644
--- a/opm/models/utils/parametersystem.cpp
+++ b/opm/models/utils/parametersystem.cpp
@@ -521,18 +521,6 @@ void printUsage(const std::string& helpPreamble,
     }
 }
 
-int noPositionalParameters_(std::function<void(const std::string&, const std::string&)>,
-                            std::set<std::string>&,
-                            std::string& errorMsg,
-                            int,
-                            const char** argv,
-                            int paramIdx,
-                            int)
-{
-    errorMsg = std::string("Illegal parameter \"")+argv[paramIdx]+"\".";
-    return 0;
-}
-
 void parseParameterFile(const std::string& fileName, bool overwrite)
 {
     std::set<std::string> seenKeys;
@@ -594,8 +582,8 @@ void parseParameterFile(const std::string& fileName, bool overwrite)
 
 std::string parseCommandLineOptions(int argc,
                                     const char **argv,
-                                    const std::string& helpPreamble,
-                                    const PositionalArgumentCallback& posArgCallback)
+                                    const PositionalArgumentCallback& posArgCallback,
+                                    const std::string& helpPreamble)
 {
     // handle the "--help" parameter
     if (!helpPreamble.empty()) {
diff --git a/opm/models/utils/parametersystem.hpp b/opm/models/utils/parametersystem.hpp
index b131ed18c..e915c8b32 100644
--- a/opm/models/utils/parametersystem.hpp
+++ b/opm/models/utils/parametersystem.hpp
@@ -191,17 +191,6 @@ void printUsage(const std::string& helpPreamble,
                 std::ostream& os = std::cerr,
                 const bool showAll = false);
 
-/// \cond 0
-int noPositionalParameters_(std::function<void(const std::string&, const std::string&)>,
-                            std::set<std::string>&,
-                            std::string& errorMsg,
-                            int,
-                            const char** argv,
-                            int paramIdx,
-                            int);
-
-/// \endcond
-
 //! \brief Callback function for command line parsing.
 using PositionalArgumentCallback = std::function<int(std::function<void(const std::string&,
                                                                         const std::string&)>,
@@ -230,8 +219,8 @@ using PositionalArgumentCallback = std::function<int(std::function<void(const st
 std::string
 parseCommandLineOptions(int argc,
                         const char **argv,
-                        const std::string& helpPreamble = "",
-                        const PositionalArgumentCallback& posArgCallback = noPositionalParameters_);
+                        const PositionalArgumentCallback& posArgCallback,
+                        const std::string& helpPreamble = "");
 
 /*!
  * \ingroup Parameter
diff --git a/opm/models/utils/start.hh b/opm/models/utils/start.hh
index 81a47c7eb..99a077282 100644
--- a/opm/models/utils/start.hh
+++ b/opm/models/utils/start.hh
@@ -131,8 +131,8 @@ static inline int setupParameters_(int argc,
     std::string s =
         Parameters::parseCommandLineOptions(argc,
                                             argv,
-                                            helpPreamble,
-                                            positionalParamCallback);
+                                            positionalParamCallback,
+                                            helpPreamble);
     if (!s.empty())
     {
         int status = 1;
diff --git a/tests/test_parametersystem.cpp b/tests/test_parametersystem.cpp
index 3c56847d0..ca94fecd3 100644
--- a/tests/test_parametersystem.cpp
+++ b/tests/test_parametersystem.cpp
@@ -78,8 +78,21 @@ BOOST_FIXTURE_TEST_CASE(GetLists, Fixture)
       "--unused-param=foo",
   };
 
-  Opm::Parameters::parseCommandLineOptions(5, argv, "",
-                                           Opm::Parameters::noPositionalParameters_);
+    auto noPositional = [](std::function<void(const std::string&,
+                                              const std::string&)>,
+                           std::set<std::string>&,
+                           std::string&,
+                           int,
+                           const char**,
+                           int,
+                           int) -> int
+                        {
+                            assert("Should not be here!");
+                            return 0;
+                        };
+
+
+  Opm::Parameters::parseCommandLineOptions(5, argv, noPositional);
 
   BOOST_CHECK_EQUAL(Opm::Parameters::IsSet<Opm::Parameters::SimpleParamBool>(), true);
   BOOST_CHECK_EQUAL(Opm::Parameters::IsSet<Opm::Parameters::SimpleParamFloat>(), true);