diff --git a/include/clang/Driver/Compilation.h b/include/clang/Driver/Compilation.h
index 3ec221f..6414ef1 100644
--- a/include/clang/Driver/Compilation.h
+++ b/include/clang/Driver/Compilation.h
@@ -32,10 +32,10 @@
 /// invocation.
 class Compilation {
   /// The driver we were created by.
-  Driver &TheDriver;
+  const Driver &TheDriver;
 
   /// The default tool chain.
-  ToolChain &DefaultToolChain;
+  const ToolChain &DefaultToolChain;
 
   /// The original (untranslated) input argument list.
   InputArgList *Args;
@@ -56,7 +56,8 @@
   ArgStringList ResultFiles;
 
 public:
-  Compilation(Driver &D, ToolChain &DefaultToolChain, InputArgList *Args);
+  Compilation(const Driver &D, const ToolChain &DefaultToolChain, 
+              InputArgList *Args);
   ~Compilation();
 
   const Driver &getDriver() const { return TheDriver; }
diff --git a/lib/Driver/Compilation.cpp b/lib/Driver/Compilation.cpp
index d7901a6..7e29b67 100644
--- a/lib/Driver/Compilation.cpp
+++ b/lib/Driver/Compilation.cpp
@@ -21,8 +21,8 @@
 #include <errno.h>
 using namespace clang::driver;
 
-Compilation::Compilation(Driver &D,
-                         ToolChain &_DefaultToolChain,
+Compilation::Compilation(const Driver &D,
+                         const ToolChain &_DefaultToolChain,
                          InputArgList *_Args) 
   : TheDriver(D), DefaultToolChain(_DefaultToolChain), Args(_Args) {
 }