diff --git a/pkgs/applications/audio/pianobar/default.nix b/pkgs/applications/audio/pianobar/default.nix
index 26b94f306bc6..811952f845ff 100644
--- a/pkgs/applications/audio/pianobar/default.nix
+++ b/pkgs/applications/audio/pianobar/default.nix
@@ -13,7 +13,7 @@ stdenv.mkDerivation rec {
     libao json_c libgcrypt ffmpeg curl
   ];
 
-  makeFlags="PREFIX=$(out)";
+  makeFlags = [ "PREFIX=$(out)" ];
 
   CC = "gcc";
   CFLAGS = "-std=c99";