diff --git a/default.nix b/default.nix
index e56dfbf39..3cb18c1b7 100644
--- a/default.nix
+++ b/default.nix
@@ -62,8 +62,10 @@ let
       { name = "postgresql-12"; postgresql = pkgs.postgresql_12.withPackages (p: [ p.postgis p.pg_safeupdate ]); }
     ];
 
+  haskellPackages = pkgs.haskell.packages."${compiler}";
+
   # Dynamic derivation for PostgREST
-  postgrest = pkgs.lib.pipe (pkgs.haskell.packages."${compiler}".callCabal2nix name src { }) [
+  postgrest = pkgs.lib.pipe (haskellPackages.callCabal2nix name src { }) [
     # To allow ghc-datasize to be used.
     lib.disableLibraryProfiling
     # We are never going to use dynamic haskell libraries anyway. "Dynamic" refers to how
@@ -84,9 +86,13 @@ rec {
 
   # Derivation for the PostgREST Haskell package, including the executable,
   # libraries and documentation. We disable running the test suite on Nix
-  # builds, as they require a database to be set up.
-  postgrestPackage =
-    lib.dontCheck postgrest;
+  # builds, as they require a database to be set up. We split the binary
+  # into a separate output, so that the default distribution via flake.nix
+  # has a much smaller closure size.
+  postgrestPackage = pkgs.lib.pipe postgrest [
+    lib.dontCheck
+    lib.enableSeparateBinOutput
+  ];
 
   # Profiled dynamic executable.
   postgrestProfiled = pkgs.lib.pipe postgrestPackage [
diff --git a/flake.nix b/flake.nix
index 24f4c50f2..16ccc1d80 100644
--- a/flake.nix
+++ b/flake.nix
@@ -33,8 +33,8 @@
     in
     {
       packages = genSystems (attrs: {
-        default = attrs.postgrestPackage;
-        profiled = attrs.postgrestProfiled;
+        default = attrs.postgrestPackage.bin;
+        profiled = attrs.postgrestProfiled.bin;
       } // nixpkgs.lib.optionalAttrs (attrs ? postgrestStatic) {
         static = attrs.postgrestStatic;
       });
@@ -42,7 +42,7 @@
       apps = genSystems (attrs: {
         default = {
           type = "app";
-          program = "${attrs.postgrestStatic or attrs.postgrestPackage}/bin/postgrest";
+          program = "${attrs.postgrestStatic or attrs.postgrestPackage.bin}/bin/postgrest";
           meta.description = "REST API for any Postgres database";
         };
       });
diff --git a/nix/tools/withTools.nix b/nix/tools/withTools.nix
index f11f92d40..82de1e4d6 100644
--- a/nix/tools/withTools.nix
+++ b/nix/tools/withTools.nix
@@ -351,12 +351,13 @@ let
         rm -f result
         if [ -z "''${PGRST_BUILD_CABAL:-}" ]; then
           echo -n "Building postgrest (nix)... "
-          nix-build -A postgrestPackage > "$tmpdir"/build.log 2>&1 || {
+          # Using lib.getBin to also make this work with older checkouts, where .bin was not a thing, yet.
+          nix-build -E 'with import ./. {}; pkgs.lib.getBin postgrestPackage' > "$tmpdir"/build.log 2>&1 || {
             echo "failed, output:"
             cat "$tmpdir"/build.log
             exit 1
           }
-          PGRST_CMD=./result/bin/postgrest
+          PGRST_CMD=$(echo ./result*/bin/postgrest)
         else
           echo -n "Building postgrest (cabal)... "
           postgrest-build