diff --git a/pkgs/development/libraries/haskell/HFuse/default.nix b/pkgs/development/libraries/haskell/HFuse/default.nix
index 7ddacbc79ac8..04ebefd37fac 100644
--- a/pkgs/development/libraries/haskell/HFuse/default.nix
+++ b/pkgs/development/libraries/haskell/HFuse/default.nix
@@ -9,11 +9,6 @@ cabal.mkDerivation (self: {
   extraLibraries = [ fuse ];
   preConfigure = ''
     sed -i -e "s@  Extra-Lib-Dirs:         /usr/local/lib@  Extra-Lib-Dirs:         ${fuse}/lib@" HFuse.cabal
-    sed -i -e "s/LANGUAGE FlexibleContexts/LANGUAGE FlexibleContexts, RankNTypes/" System/Fuse.hsc
-    sed -i -e "s/E(Exception/E(catch, Exception, IOException/" System/Fuse.hsc
-    sed -i -e "s/IO(catch,/IO(/" System/Fuse.hsc
-    sed -i -e "s/IO.catch/ E.catch/" System/Fuse.hsc
-    sed -i -e "s/const exitFailure/\\\\(_ :: IOException) -> exitFailure/" System/Fuse.hsc
   '';
   meta = {
     homepage = "https://github.com/m15k/hfuse";
diff --git a/pkgs/development/libraries/haskell/jmacro-rpc-happstack/default.nix b/pkgs/development/libraries/haskell/jmacro-rpc-happstack/default.nix
index 124032b9a0bd..c8c7c503ea93 100644
--- a/pkgs/development/libraries/haskell/jmacro-rpc-happstack/default.nix
+++ b/pkgs/development/libraries/haskell/jmacro-rpc-happstack/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, aeson, blazeHtml, happstackServer, jmacro, jmacroRpc, mtl
 }:
 
diff --git a/pkgs/development/libraries/haskell/jmacro-rpc-snap/default.nix b/pkgs/development/libraries/haskell/jmacro-rpc-snap/default.nix
index 356cb2435959..9ff082e3239f 100644
--- a/pkgs/development/libraries/haskell/jmacro-rpc-snap/default.nix
+++ b/pkgs/development/libraries/haskell/jmacro-rpc-snap/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, aeson, jmacro, jmacroRpc, mtl, snapCore }:
 
 cabal.mkDerivation (self: {
diff --git a/pkgs/development/libraries/haskell/jmacro-rpc/default.nix b/pkgs/development/libraries/haskell/jmacro-rpc/default.nix
index 24044fdb1f34..d1e302b1bc9f 100644
--- a/pkgs/development/libraries/haskell/jmacro-rpc/default.nix
+++ b/pkgs/development/libraries/haskell/jmacro-rpc/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, aeson, attoparsec, blazeHtml, contravariant, jmacro, mtl
 , scientific, split, text, unorderedContainers, vector
 }:
diff --git a/pkgs/development/libraries/haskell/jmacro/default.nix b/pkgs/development/libraries/haskell/jmacro/default.nix
index 50932d1b5172..32d4d3747ef9 100644
--- a/pkgs/development/libraries/haskell/jmacro/default.nix
+++ b/pkgs/development/libraries/haskell/jmacro/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, aeson, haskellSrcExts, haskellSrcMeta, mtl, parseargs
 , parsec, regexPosix, safe, syb, text, unorderedContainers, vector
 , wlPprintText