diff --git a/tools/extract/extract.cpp b/tools/extract/extract.cpp
index cfadff0..e904bea 100644
--- a/tools/extract/extract.cpp
+++ b/tools/extract/extract.cpp
@@ -92,7 +92,7 @@
 
   std::auto_ptr<Module> M(ParseBytecodeFile(InputFilename));
   if (M.get() == 0) {
-    std::cerr << "bytecode didn't read correctly.\n";
+    std::cerr << argv[0] << ": bytecode didn't read correctly.\n";
     return 1;
   }