diff --git a/CheckFunctionUsage.cpp b/CheckFunctionUsage.cpp
index 136a1939a..056974e5b 100644
--- a/CheckFunctionUsage.cpp
+++ b/CheckFunctionUsage.cpp
@@ -146,7 +146,9 @@ void CheckFunctionUsage::check()
             continue;
         if ( ! func.usedSameFile )
         {
-            std::ostringstream errmsg;
+            std::ostringstream errmsg;
+            if ( func.filename != "+" )
+                errmsg << "[" << func.filename << "] ";
             errmsg << "The function '" << it->first << "' is never used.";
             _errorLogger->reportErr( errmsg.str() );
         }