diff --git a/pkgs/development/libraries/haskell/ekg-carbon/default.nix b/pkgs/development/libraries/haskell/ekg-carbon/default.nix
index 6f3fbb31142d..12c29f0d56e5 100644
--- a/pkgs/development/libraries/haskell/ekg-carbon/default.nix
+++ b/pkgs/development/libraries/haskell/ekg-carbon/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, ekgCore, network, networkCarbon, text, time
 , unorderedContainers, vector
 }:
diff --git a/pkgs/development/libraries/haskell/engine-io-snap/default.nix b/pkgs/development/libraries/haskell/engine-io-snap/default.nix
index fdef92cfab86..07ccb6c71520 100644
--- a/pkgs/development/libraries/haskell/engine-io-snap/default.nix
+++ b/pkgs/development/libraries/haskell/engine-io-snap/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, attoparsecEnumerator, engineIo, snapCore
 , unorderedContainers, websockets, websocketsSnap
 }:
diff --git a/pkgs/development/libraries/haskell/engine-io/default.nix b/pkgs/development/libraries/haskell/engine-io/default.nix
index 027e621b482e..d9a48cd80dd0 100644
--- a/pkgs/development/libraries/haskell/engine-io/default.nix
+++ b/pkgs/development/libraries/haskell/engine-io/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, aeson, async, attoparsec, base64Bytestring, either
 , monadLoops, mwcRandom, stm, text, transformers
 , unorderedContainers, vector, websockets
diff --git a/pkgs/development/libraries/haskell/network-carbon/default.nix b/pkgs/development/libraries/haskell/network-carbon/default.nix
index 15749d07a1b7..d5a4c64cff8a 100644
--- a/pkgs/development/libraries/haskell/network-carbon/default.nix
+++ b/pkgs/development/libraries/haskell/network-carbon/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, network, text, time, vector }:
 
 cabal.mkDerivation (self: {
diff --git a/pkgs/development/libraries/haskell/simple-conduit/default.nix b/pkgs/development/libraries/haskell/simple-conduit/default.nix
index ef1a5c40278e..a55267d426b1 100644
--- a/pkgs/development/libraries/haskell/simple-conduit/default.nix
+++ b/pkgs/development/libraries/haskell/simple-conduit/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, bifunctors, chunkedData, either, exceptions, filepath
 , free, liftedAsync, liftedBase, mmorph, monadControl
 , monoTraversable, mtl, mwcRandom, primitive, semigroups, stm
diff --git a/pkgs/development/libraries/haskell/socket-io/default.nix b/pkgs/development/libraries/haskell/socket-io/default.nix
index 65179c1dbaf6..324a2b046162 100644
--- a/pkgs/development/libraries/haskell/socket-io/default.nix
+++ b/pkgs/development/libraries/haskell/socket-io/default.nix
@@ -1,3 +1,5 @@
+# This file was auto-generated by cabal2nix. Please do NOT edit manually!
+
 { cabal, aeson, attoparsec, engineIo, mtl, stm, text, transformers
 , unorderedContainers, vector
 }: