diff --git a/pkgs/development/compilers/opa/default.nix b/pkgs/development/compilers/opa/default.nix
index 3f6e3956f36..6df16e44c3d 100644
--- a/pkgs/development/compilers/opa/default.nix
+++ b/pkgs/development/compilers/opa/default.nix
@@ -58,6 +58,6 @@ stdenv.mkDerivation rec {
     homepage = http://opalang.org/;
     license = stdenv.lib.licenses.gpl3;
     maintainers = [ stdenv.lib.maintainers.kkallio ];
-    platforms = "x86_64-linux";
+    platforms = [ "x86_64-linux" ];
   };
 }