diff --git a/pkgs/development/compilers/hhvm/default.nix b/pkgs/development/compilers/hhvm/default.nix
index d976b6edab84..23f0484e8ead 100644
--- a/pkgs/development/compilers/hhvm/default.nix
+++ b/pkgs/development/compilers/hhvm/default.nix
@@ -26,7 +26,7 @@ stdenv.mkDerivation rec {
       gmp libyaml libedit libvpx imagemagick fribidi gperf
     ];
 
-  enableParallelBuilding = true;
+  enableParallelBuilding = false; # occasional build problems;
   dontUseCmakeBuildDir = true;
   NIX_LDFLAGS = "-lpam -L${pam}/lib";
   MYSQL_INCLUDE_DIR="${mariadb}/include/mysql";