diff --git a/lib/Lex/LiteralSupport.cpp b/lib/Lex/LiteralSupport.cpp
index f9fd1aa..8c2f2af 100644
--- a/lib/Lex/LiteralSupport.cpp
+++ b/lib/Lex/LiteralSupport.cpp
@@ -224,7 +224,7 @@
       saw_period = true;
       s = SkipDigits(s);
     } 
-    if (*s == 'e' || *s == 'E') { // exponent
+    if (s != ThisTokEnd && (*s == 'e' || *s == 'E')) { // exponent
       const char *Exponent = s;
       s++;
       saw_exponent = true;