diff --git a/pkgs/development/compilers/ghc/8.6.4.nix b/pkgs/development/compilers/ghc/8.6.4.nix
index 6cd7522bae8..640709aba1b 100644
--- a/pkgs/development/compilers/ghc/8.6.4.nix
+++ b/pkgs/development/compilers/ghc/8.6.4.nix
@@ -96,11 +96,20 @@ stdenv.mkDerivation (rec {
 
   outputs = [ "out" "doc" ];
 
-  patches = [(fetchpatch rec { # https://phabricator.haskell.org/D5123
-    url = "http://tarballs.nixos.org/sha256/${sha256}";
-    name = "D5123.diff";
-    sha256 = "0nhqwdamf2y4gbwqxcgjxs0kqx23w9gv5kj0zv6450dq19rji82n";
-  })];
+  patches = [
+    (fetchpatch rec { # https://phabricator.haskell.org/D5123
+     url = "http://tarballs.nixos.org/sha256/${sha256}";
+     name = "D5123.diff";
+     sha256 = "0nhqwdamf2y4gbwqxcgjxs0kqx23w9gv5kj0zv6450dq19rji82n";
+    })
+    (fetchpatch rec { # https://github.com/haskell/haddock/issues/900
+     url = "https://patch-diff.githubusercontent.com/raw/haskell/haddock/pull/983.diff";
+     name = "loadpluginsinmodules.diff";
+     sha256 = "0bvvv0zsfq2581zsir97zfkggc1kkircbbajc2fz3b169ycpbha1";
+     extraPrefix = "utils/haddock/";
+     stripLen = 1;
+   })
+  ];
 
   postPatch = "patchShebangs .";