diff --git a/pkgs/development/compilers/hhvm/default.nix b/pkgs/development/compilers/hhvm/default.nix
index a66b2264f073..1cb28118ccbe 100644
--- a/pkgs/development/compilers/hhvm/default.nix
+++ b/pkgs/development/compilers/hhvm/default.nix
@@ -53,6 +53,7 @@ stdenv.mkDerivation rec {
       hphp/runtime/ext/std/*.cpp \
       hphp/runtime/ext_zend_compat/php-src/main/*.cpp \
       hphp/runtime/ext_zend_compat/php-src/main/*.h
+    sed '1i#include <functional>' -i third-party/mcrouter/src/mcrouter/lib/cycles/Cycles.h
     patchShebangs .
   '';