1 files changed, 2 insertions, 2 deletions
diff --git a/include/clang/Lex/TokenConcatenation.h b/include/clang/Lex/TokenConcatenation.h
index 60c182b509a4d..3199e36f0d269 100644
--- a/include/clang/Lex/TokenConcatenation.h
+++ b/include/clang/Lex/TokenConcatenation.h
@@ -29,7 +29,7 @@ namespace clang {
   /// and ")" next to each other is safe.
   ///
   class TokenConcatenation {
-    Preprocessor &PP;
+    const Preprocessor &PP;
 
     enum AvoidConcatInfo {
       /// By default, a token never needs to avoid concatenation.  Most tokens
@@ -56,7 +56,7 @@ namespace clang {
     /// method.
     char TokenInfo[tok::NUM_TOKENS];
   public:
-    TokenConcatenation(Preprocessor &PP);
+    TokenConcatenation(const Preprocessor &PP);
 
     bool AvoidConcat(const Token &PrevPrevTok,
                      const Token &PrevTok,