diff --git a/include/xeus/xhelper.hpp b/include/xeus/xhelper.hpp
index 6ff3b692..c06354a6 100644
--- a/include/xeus/xhelper.hpp
+++ b/include/xeus/xhelper.hpp
@@ -24,7 +24,7 @@ namespace xeus
 {
     XEUS_API std::string get_start_message(const xconfiguration& config);
 
-    XEUS_API std::string extract_filename(int argc, char* argv[]);
+    XEUS_API std::string extract_filename(int &argc, char* argv[]);
 
     XEUS_API bool should_print_version(int argc, char* argv[]);
 
diff --git a/src/xhelper.cpp b/src/xhelper.cpp
index 98d999f3..783cc6a4 100644
--- a/src/xhelper.cpp
+++ b/src/xhelper.cpp
@@ -30,7 +30,7 @@ namespace xeus
         return kernel_info;
     }
 
-    std::string extract_filename(int argc, char* argv[])
+    std::string extract_filename(int &argc, char* argv[])
     {
         std::string res = "";
         for (int i = 0; i < argc; ++i)
diff --git a/test/test_unit_kernel.cpp b/test/test_unit_kernel.cpp
index 97a967ee..1acb78c5 100644
--- a/test/test_unit_kernel.cpp
+++ b/test/test_unit_kernel.cpp
@@ -55,11 +55,13 @@ namespace xeus
 
         TEST_CASE("extract_filename")
         {
+            int argc = 3;
             char* argv[2];
             argv[0] = (char*)"-f";
             argv[1] = (char*)"connection.json";
-            std::string file_name = extract_filename(3, argv);
+            std::string file_name = extract_filename(argc, argv);
             REQUIRE_EQ(file_name, "connection.json");
+            REQUIRE_EQ(argc, 1);
         }
 
         TEST_CASE("should_print_version")