diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 94ea99db8a1..96b9047501b 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,11 @@
+2016-10-04  Kelvin Nilsen  <kelvin@gcc.gnu.org>
+
+	PR target/77847
+	* lex.c (search_line_fast): Add a FALLTHROUGH comment to correct
+	compiler error in the version of this function that is
+	conditionally compiled when GCC_VERSION >= 4005 and both
+	__ALTIVEC__ and __BIG_ENDIAN__ symbols are defined.
+
 2016-09-26  Marek Polacek  <polacek@redhat.com>
 	    Jakub Jelinek  <jakub@redhat.com>
 
diff --git a/libcpp/lex.c b/libcpp/lex.c
index 0c47e298070..6d2e596e2d4 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -733,6 +733,7 @@ search_line_fast (const uchar *s, const uchar *end ATTRIBUTE_UNUSED)
 	if (l != 0)
 	  break;
 	s += sizeof(unsigned long);
+	/* FALLTHROUGH */
       case 2:
 	l = u.l[i++];
 	if (l != 0)