diff --git a/default.nix b/default.nix
index 0a0b4feb1..770920563 100644
--- a/default.nix
+++ b/default.nix
@@ -26,12 +26,15 @@ let
       sha256 = nixpkgsVersion.tarballHash;
     };
 
+  allOverlays =
+    import nix/overlays;
+
   overlays =
     [
-      (import nix/overlays/postgresql-default.nix)
-      (import nix/overlays/postgresql-legacy.nix)
-      (import nix/overlays/gitignore.nix)
-      (import nix/overlays/haskell-packages { inherit compiler; })
+      allOverlays.postgresql-default
+      allOverlays.postgresql-legacy
+      allOverlays.gitignore
+      (allOverlays.haskell-packages { inherit compiler; })
     ];
 
   # Evaluated expression of the Nixpkgs repository.
@@ -55,13 +58,14 @@ let
   drv =
     pkgs.haskell.packages."${compiler}".callCabal2nix name src { };
 
-  # Static set of Haskell Packages based on nh2/static-haskell-nix
-  staticHaskellPackages =
-    import nix/static-haskell-packages.nix { inherit nixpkgs compiler patches; };
+  # Function that derives a fully static Haskell package based on
+  # nh2/static-haskell-nix
+  staticHaskellPackage =
+    import nix/static-haskell-package.nix { inherit nixpkgs compiler patches allOverlays; };
 
   # Static derivation for the PostgREST executable.
   drvStatic =
-    staticHaskellPackages.callCabal2nix name src { };
+    staticHaskellPackage name src;
 
   lib =
     pkgs.haskell.lib;
diff --git a/nix/nixpkgs-version.nix b/nix/nixpkgs-version.nix
index fca55e589..c0bad98c0 100644
--- a/nix/nixpkgs-version.nix
+++ b/nix/nixpkgs-version.nix
@@ -1,6 +1,6 @@
 # Pinned version of Nixpkgs, generated with nixpkgs-upgrade.
 {
-  date = "2020-05-19";
-  rev = "0f5ce2fac0c726036ca69a5524c59a49e2973dd4";
-  tarballHash = "0nkk492aa7pr0d30vv1aw192wc16wpa1j02925pldc09s9m9i0r3";
+  date = "2020-05-21";
+  rev = "6405edf2dca7f6faaa29266136dfa7f8f969b511";
+  tarballHash = "069skn0ayxmhdlw1xcj92cij7wydkk2bndkcyk4vvhms16p9wj46";
 }
diff --git a/nix/overlays/default.nix b/nix/overlays/default.nix
new file mode 100644
index 000000000..b52781049
--- /dev/null
+++ b/nix/overlays/default.nix
@@ -0,0 +1,6 @@
+{
+  gitignore = import ./gitignore.nix;
+  haskell-packages = import ./haskell-packages;
+  postgresql-default = import ./postgresql-default.nix;
+  postgresql-legacy = import ./postgresql-legacy.nix;
+}
diff --git a/nix/overlays/haskell-packages/Cabal.nix b/nix/overlays/haskell-packages/Cabal.nix
deleted file mode 100644
index 879af3381..000000000
--- a/nix/overlays/haskell-packages/Cabal.nix
+++ /dev/null
@@ -1,90 +0,0 @@
-{ mkDerivation
-, array
-, base
-, base-compat
-, base-orphans
-, binary
-, bytestring
-, containers
-, deepseq
-, Diff
-, directory
-, filepath
-, integer-logarithms
-, mtl
-, optparse-applicative
-, parsec
-, pretty
-, process
-, QuickCheck
-, stdenv
-, stm
-, tagged
-, tar
-, tasty
-, tasty-golden
-, tasty-hunit
-, tasty-quickcheck
-, temporary
-, text
-, time
-, transformers
-, tree-diff
-, unix
-}:
-mkDerivation {
-  pname = "Cabal";
-  version = "3.0.0.0";
-  sha256 = "5143ec26d740c1a508c93a8860e64407e7546c29b9817db20ff1595c1968d287";
-  setupHaskellDepends = [ mtl parsec ];
-  libraryHaskellDepends = [
-    array
-    base
-    binary
-    bytestring
-    containers
-    deepseq
-    directory
-    filepath
-    mtl
-    parsec
-    pretty
-    process
-    text
-    time
-    transformers
-    unix
-  ];
-  testHaskellDepends = [
-    array
-    base
-    base-compat
-    base-orphans
-    binary
-    bytestring
-    containers
-    deepseq
-    Diff
-    directory
-    filepath
-    integer-logarithms
-    optparse-applicative
-    pretty
-    process
-    QuickCheck
-    stm
-    tagged
-    tar
-    tasty
-    tasty-golden
-    tasty-hunit
-    tasty-quickcheck
-    temporary
-    text
-    tree-diff
-  ];
-  doCheck = false;
-  homepage = "http://www.haskell.org/cabal/";
-  description = "A framework for packaging Haskell software";
-  license = stdenv.lib.licenses.bsd3;
-}
diff --git a/nix/overlays/haskell-packages/default.nix b/nix/overlays/haskell-packages/default.nix
index 7fe81485d..943b27cb8 100644
--- a/nix/overlays/haskell-packages/default.nix
+++ b/nix/overlays/haskell-packages/default.nix
@@ -1,10 +1,7 @@
-{ compiler, static ? false }:
+{ compiler, extraOverrides ? (final: prev: { }) }:
 
 self: super:
 let
-  lib =
-    self.haskell.lib;
-
   overrides =
     final: prev:
     rec {
@@ -15,16 +12,7 @@ let
             ver = "0.3.0";
             sha256 = "0iwh4wsjhb7pms88lw1afhdal9f86nrrkkvv65f9wxbd1b159n72";
           } { };
-
-      cabal2nix =
-        if static then
-        # cabal2nix depends on Cabal 3.0.*, while our pinned version of
-        # Nixpkgs only provides 2.4 or 3.2. So we pinned 3.0.0.0 in
-        # ./Cabal.nix
-          prev.cabal2nix.overrideScope (self: super: { Cabal = self.callPackage ./Cabal.nix { }; })
-        else
-          prev.cabal2nix;
-    };
+    } // extraOverrides final prev;
 in
 {
   haskell =
diff --git a/nix/patches/default.nix b/nix/patches/default.nix
index 4f0acd54e..97d470b25 100644
--- a/nix/patches/default.nix
+++ b/nix/patches/default.nix
@@ -26,4 +26,9 @@
   # See: https://github.com/NixOS/nixpkgs/pull/87879
   nixpkgs-openssl-split-runtime-dependencies-of-static-builds =
     ./nixpkgs-openssl-split-runtime-dependencies-of-static-builds.patch;
+
+  # Fix how openssl is linked on static builds, see:
+  # https://github.com/nh2/static-haskell-nix/pull/91
+  static-haskell-nix-postgrest-openssl-linking-fix =
+    ./static-haskell-nix-postgrest-openssl-linking-fix.patch;
 }
diff --git a/nix/patches/static-haskell-nix-postgrest-openssl-linking-fix.patch b/nix/patches/static-haskell-nix-postgrest-openssl-linking-fix.patch
new file mode 100644
index 000000000..56919a73f
--- /dev/null
+++ b/nix/patches/static-haskell-nix-postgrest-openssl-linking-fix.patch
@@ -0,0 +1,25 @@
+From bb4c1e27e391eff01591fe60830ff68a9ada41ef Mon Sep 17 00:00:00 2001
+From: Remo <remo>
+Date: Wed, 22 Apr 2020 11:58:07 +0200
+Subject: [PATCH] Add postgrest libpq linking fix
+
+---
+ survey/default.nix | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/survey/default.nix b/survey/default.nix
+index b28606c..fd7cde7 100644
+--- a/survey/default.nix
++++ b/survey/default.nix
+@@ -1052,6 +1052,11 @@ let
+                   super.squeal-postgresql
+                   [ final.openssl ]
+                   "--libs openssl";
++              postgrest =
++                addStaticLinkerFlagsWithPkgconfig
++                  super.postgrest
++                  [ final.openssl ]
++                  "--libs openssl";
+ 
+               xml-to-json =
+                 addStaticLinkerFlagsWithPkgconfig
diff --git a/nix/static-haskell-packages.nix b/nix/static-haskell-package.nix
similarity index 51%
rename from nix/static-haskell-packages.nix
rename to nix/static-haskell-package.nix
index 37deee982..cfb4dc633 100644
--- a/nix/static-haskell-packages.nix
+++ b/nix/static-haskell-package.nix
@@ -1,5 +1,7 @@
-# Derive a fully static set of Haskell packages based on musl instead of glibc.
-{ nixpkgs, compiler, patches }:
+# Derive a fully static Haskell package based on musl instead of glibc.
+{ nixpkgs, compiler, patches, allOverlays }:
+
+name: src:
 let
   # The nh2/static-haskell-nix project does all the hard work for us.
   static-haskell-nix =
@@ -11,6 +13,13 @@ let
       sha256 = "155spda2lww378bhx68w6dxwqd5y6s9kin3qbgl2m23r3vmk3m3w";
     };
 
+  patched-static-haskell-nix =
+    patches.applyPatches "patched-static-haskell-nix"
+      static-haskell-nix
+      [
+        patches.static-haskell-nix-postgrest-openssl-linking-fix
+      ];
+
   patchedNixpkgs =
     patches.applyPatches "patched-nixpkgs"
       nixpkgs
@@ -19,9 +28,20 @@ let
         patches.nixpkgs-openssl-split-runtime-dependencies-of-static-builds
       ];
 
+  extraOverrides =
+    final: prev:
+    rec {
+      # We need to add our package needs to the package set that we pass to
+      # static-haskell-nix. Using callCabal2nix on the haskellPackages that
+      # it returns would result in a dynamic build based on musl, and not the
+      # fully static build that we want.
+      "${name}" =
+        prev.callCabal2nix name src { };
+    };
+
   overlays =
     [
-      (import overlays/haskell-packages { inherit compiler; static = true; })
+      (allOverlays.haskell-packages { inherit compiler extraOverrides; })
     ];
 
   # Apply our overlay to the given pkgs.
@@ -37,6 +57,6 @@ let
   # The static-haskell-nix 'survey' derives a full static set of Haskell
   # packages, applying fixes where necessary.
   survey =
-    import "${static-haskell-nix}/survey" { inherit normalPkgs compiler defaultCabalPackageVersionComingWithGhc; };
+    import "${patched-static-haskell-nix}/survey" { inherit normalPkgs compiler defaultCabalPackageVersionComingWithGhc; };
 in
-survey.haskellPackages
+survey.haskellPackages."${name}"