diff --git a/pkgs/development/libraries/webkit2-sharp/default.nix b/pkgs/development/libraries/webkit2-sharp/default.nix
index b8a476b3b33..de10fff43da 100644
--- a/pkgs/development/libraries/webkit2-sharp/default.nix
+++ b/pkgs/development/libraries/webkit2-sharp/default.nix
@@ -33,6 +33,14 @@ stdenv.mkDerivation rec {
     webkitgtk
   ];
 
+  postPatch = ''
+    # Workaround build failure with WebKitGTK 2.40.0
+    # https://github.com/hbons/webkit2-sharp/issues/6
+    substituteInPlace sources/webkit2-sharp-api.raw --replace \
+      '<field cname="parentInstance" access="public" writeable="false" readable="true" name="ParentInstance" type="GtkContainer*"/>' \
+      '<field cname="parent" access="public" writeable="false" readable="true" name="Parent" type="GtkContainer*"/>'
+  '';
+
   ac_cv_path_MONODOCER = "no";
   installFlagsArray = ["GAPIXMLDIR=/tmp/gapixml"];