diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 84887683337..9387bb079c6 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2017-06-13  Marek Polacek  <polacek@redhat.com>
+
+	PR objc/80949
+	* c-warn.c (do_warn_duplicated_branches): Return if any of the
+	branches is null.
+
 2017-06-13  Martin Liska  <mliska@suse.cz>
 
 	PR sanitize/78204
diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c
index 35321a6cb1b..056a058ca77 100644
--- a/gcc/c-family/c-warn.c
+++ b/gcc/c-family/c-warn.c
@@ -2354,8 +2354,8 @@ do_warn_duplicated_branches (tree expr)
   tree thenb = COND_EXPR_THEN (expr);
   tree elseb = COND_EXPR_ELSE (expr);
 
-  /* Don't bother if there's no else branch.  */
-  if (elseb == NULL_TREE)
+  /* Don't bother if any of the branches is missing.  */
+  if (thenb == NULL_TREE || elseb == NULL_TREE)
     return;
 
   /* And don't warn for empty statements.  */