diff --git a/src/main.cpp b/src/main.cpp
index 9002f7c..216e5a6 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -58,9 +58,10 @@ std::ostream& help(std::ostream& out) {
     << "   -f,   --ref-file | get referenced files.\n"
     << "   -dbg, --debug    | debug mode.\n"
     << "         --prof     | show profiling result, available in debug mode.\n"
-    << "         --prof-all | show profiling result of all files,"
+    << "         --prof-all | show profiling result of all files, "
     << "available under debug mode.\n"
-    << "         --limit    | use limited execution mode."
+    << "         --limit    | use limited execution mode "
+    << "(readonly api enabled).\n"
     << "file:\n"
     << "   <filename>       | execute file.\n"
     << "argv:\n"