diff --git a/util.cpp b/util.cpp
index 933b01b..2540fe9 100644
--- a/util.cpp
+++ b/util.cpp
@@ -61,7 +61,8 @@
 
     if (!ifs.is_open())
     {
-        std::fprintf(stderr, "Unable to open file %s.\n", fileName.c_str());
+        auto msg = std::string("Unable to open file ") + fileName.c_str();
+        log<level::DEBUG>(msg.c_str());
     }
     else
     {