diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index 2e785570113..b87ddf9c95b 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -153,6 +153,7 @@ readExponent(StringRef::iterator begin, StringRef::iterator end)
     value += absExponent * 10;
     if (absExponent >= overlargeExponent) {
       absExponent = overlargeExponent;
+      p = end;  /* outwit assert below */
       break;
     }
     absExponent = value;