diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index 13bda71127ffc56caf509033fee58d0e32ec42f0..1f1a32a2b2cc90dac3026b8a80cf16c5778d7e12 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/lib/Format/TokenAnnotator.cpp
@@ -1140,7 +1140,7 @@ private:
 
     FormatToken *LeftOfParens = Tok.MatchingParen->getPreviousNonComment();
     if (LeftOfParens) {
-      // If there is an opening parenthesis left of the current parentheses,
+      // If there is a closing parenthesis left of the current parentheses,
       // look past it as these might be chained casts.
       if (LeftOfParens->is(tok::r_paren)) {
         if (!LeftOfParens->MatchingParen ||
@@ -1159,7 +1159,7 @@ private:
       // Certain other tokens right before the parentheses are also signals that
       // this cannot be a cast.
       if (LeftOfParens->isOneOf(tok::at, tok::r_square, TT_OverloadedOperator,
-                                TT_TemplateCloser))
+                                TT_TemplateCloser, tok::ellipsis))
         return false;
     }
 
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index d27da34d3406e61c081db3b9c599e5a054f1d790..7e3b4ce3571712f3b6e057bdd5ce51f34dc1bbfb 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -5494,6 +5494,7 @@ TEST_F(FormatTest, UnderstandsTemplateParameters) {
 
 TEST_F(FormatTest, UnderstandsBinaryOperators) {
   verifyFormat("COMPARE(a, ==, b);");
+  verifyFormat("auto s = sizeof...(Ts) - 1;");
 }
 
 TEST_F(FormatTest, UnderstandsPointersToMembers) {