diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c109ca7ae7c..b1eeaf3fa9b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-01-16  David Malcolm  <dmalcolm@redhat.com>
+
+	PR bootstrap/78616
+	* system.h: Poison strndup.
+
 2017-01-16  Alan Modra  <amodra@gmail.com>
 
 	PR target/79098
diff --git a/gcc/system.h b/gcc/system.h
index 0cd58dba110..c0f08a99ed1 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -840,7 +840,8 @@ extern void fancy_abort (const char *, int, const char *) ATTRIBUTE_NORETURN;
 #ifndef USES_ISL
 #undef calloc
 #undef strdup
- #pragma GCC poison calloc strdup
+#undef strndup
+ #pragma GCC poison calloc strdup strndup
 #endif
 
 #if !defined(FLEX_SCANNER) && !defined(YYBISON)