diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 98c2d28..24f88d9 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -403,6 +403,8 @@
   Args.AddAllArgs(CmdArgs, options::OPT_fauto_module_import);
 
   // Parse additional include paths from environment variables.
+  // FIXME: We should probably sink the logic for handling these from the
+  // frontend into the driver. It will allow deleting 4 otherwise unused flags.
   // CPATH - included following the user specified includes (but prior to
   // builtin and standard includes).
   AddIncludeDirectoryList(Args, CmdArgs, "-I", ::getenv("CPATH"));