diff --git a/tests/functional_tests/difficulty_analysis.cpp b/tests/functional_tests/difficulty_analysis.cpp
index 2a6c2500..c089c113 100644
--- a/tests/functional_tests/difficulty_analysis.cpp
+++ b/tests/functional_tests/difficulty_analysis.cpp
@@ -16,7 +16,7 @@ using namespace epee;
 
 void run_difficulty_analysis(const std::string& path)
 {
-  std::istringstream fstr(path);
+  std::ifstream fstr(path);
   if (!fstr.good())
   {
     LOG_ERROR("unable to open " << path);
@@ -41,4 +41,3 @@ void run_difficulty_analysis(const std::string& path)
 
   return;
 }
-
diff --git a/tests/functional_tests/main.cpp b/tests/functional_tests/main.cpp
index b122205c..d53e5f6c 100644
--- a/tests/functional_tests/main.cpp
+++ b/tests/functional_tests/main.cpp
@@ -103,6 +103,8 @@ int main(int argc, char* argv[])
   command_line::add_arg(desc_options, arg_generate_test_genesis_json);
   command_line::add_arg(desc_options, arg_max_tx_in_pool);
   command_line::add_arg(desc_options, arg_deadlock_guard);
+  command_line::add_arg(desc_options, arg_difficulty_analysis);
+