1 files changed, 2 insertions, 1 deletions
diff --git a/lib/Lex/PPCaching.cpp b/lib/Lex/PPCaching.cpp
index 53aa09c130..808787864b 100644
--- a/lib/Lex/PPCaching.cpp
+++ b/lib/Lex/PPCaching.cpp
@@ -102,7 +102,8 @@ void Preprocessor::AnnotatePreviousCachedTokens(const Token &Tok) {
       assert((BacktrackPositions.empty() || BacktrackPositions.back() < i) &&
              "The backtrack pos points inside the annotated tokens!");
       // Replace the cached tokens with the single annotation token.
-      CachedTokens.erase(AnnotBegin + 1, CachedTokens.begin() + CachedLexPos);
+      if (i < CachedLexPos)
+        CachedTokens.erase(AnnotBegin + 1, CachedTokens.begin() + CachedLexPos);
       *AnnotBegin = Tok;
       CachedLexPos = i;
       return;