diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index da24667..c6d2362 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1951,7 +1951,7 @@
 
   // If there are no arguments specified, warn with -Wformat-security, otherwise
   // warn only with -Wformat-nonliteral.
-  if (Args.size() == format_idx+1)
+  if (Args.size() == firstDataArg)
     Diag(Args[format_idx]->getLocStart(),
          diag::warn_format_nonliteral_noargs)
       << OrigFormatExpr->getSourceRange();
diff --git a/test/Sema/format-strings.c b/test/Sema/format-strings.c
index ba12721..6da027e 100644
--- a/test/Sema/format-strings.c
+++ b/test/Sema/format-strings.c
@@ -591,3 +591,13 @@
   printf("%n", (ip_t)0); // No warning.
   printf("%n", (cip_t)0); // expected-warning{{format specifies type 'int *' but the argument has type 'cip_t' (aka 'const int *')}}
 }
+
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+#pragma GCC diagnostic warning "-Wformat-security"
+// <rdar://problem/14178260>
+extern void test_format_security_extra_args(const char*, int, ...)
+    __attribute__((__format__(__printf__, 1, 3)));
+void test_format_security_pos(char* string) {
+  test_format_security_extra_args(string, 5); // expected-warning {{format string is not a string literal (potentially insecure)}}
+}
+#pragma GCC diagnostic warning "-Wformat-nonliteral"