diff --git a/doc/manual/installation/installing-binary.xml b/doc/manual/installation/installing-binary.xml
index d25c46b85..64c7a37fb 100644
--- a/doc/manual/installation/installing-binary.xml
+++ b/doc/manual/installation/installing-binary.xml
@@ -97,7 +97,7 @@ $ rm -rf /nix
     installation on your system:
   </para>
 
-  <screen>sh &lt;(curl https://nixos.org/nix/install) --daemon</screen>
+  <screen>sh &lt;(curl -L https://nixos.org/nix/install) --daemon</screen>
 
   <para>
     The multi-user installation of Nix will create build users between
@@ -178,7 +178,7 @@ sudo rm /Library/LaunchDaemons/org.nixos.nix-daemon.plist
     is a bit of a misnomer). To use this approach, just install Nix with:
   </para>
 
-  <screen>$ sh &lt;(curl https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume</screen>
+  <screen>$ sh &lt;(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume</screen>
 
   <para>
     If you don't like the sound of this, you'll want to weigh the
@@ -429,7 +429,7 @@ LABEL=Nix\040Store /nix apfs rw,nobrowse
   NixOS.org installation script:
 
   <screen>
-  sh &lt;(curl https://nixos.org/nix/install)
+  sh &lt;(curl -L https://nixos.org/nix/install)
 </screen>
   </para>
 
diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 157e8ddb4..00c9d540b 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -526,7 +526,7 @@ This script is going to call sudo a lot. Normally, it would show you
 exactly what commands it is running and why. However, the script is
 run in a headless fashion, like this:
 
-  $ curl https://nixos.org/nix/install | sh
+  $ curl -L https://nixos.org/nix/install | sh
 
 or maybe in a CI pipeline. Because of that, we're going to skip the
 verbose output in the interest of brevity.
@@ -534,7 +534,7 @@ verbose output in the interest of brevity.
 If you would like to
 see the output, try like this:
 
-  $ curl -o install-nix https://nixos.org/nix/install
+  $ curl -L -o install-nix https://nixos.org/nix/install
   $ sh ./install-nix
 
 EOF
diff --git a/scripts/install-nix-from-closure.sh b/scripts/install-nix-from-closure.sh
index 826ca8b8c..5824c2217 100644
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -113,7 +113,7 @@ if [ "$(uname -s)" = "Darwin" ]; then
         (
             echo ""
             echo "Installing on macOS >=10.15 requires relocating the store to an apfs volume."
-            echo "Use sh <(curl https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume or run the preparation steps manually."
+            echo "Use sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume or run the preparation steps manually."
             echo "See https://nixos.org/nix/manual/#sect-macos-installation"
             echo ""
         ) >&2
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 6c49075ba..42551ef6b 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -404,7 +404,7 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
 {
     auto path = store.parseStorePath(readString(in));
     auto hashAlgo = readString(in);
-    const auto hash = readString(in);
+    auto hash = readString(in);
 
     std::optional<FixedOutputHash> fsh;
     if (hashAlgo != "") {
@@ -413,7 +413,7 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
             method = FileIngestionMethod::Recursive;
             hashAlgo = string(hashAlgo, 2);
         }
-        const HashType hashType = parseHashType(hashAlgo);
+        auto hashType = parseHashType(hashAlgo);
         fsh = FixedOutputHash {
             .method = std::move(method),
             .hash = Hash(hash, hashType),
@@ -463,11 +463,16 @@ Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv)
 void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv)
 {
     out << drv.outputs.size();
-    for (auto & i : drv.outputs)
+    for (auto & i : drv.outputs) {
         out << i.first
-            << store.printStorePath(i.second.path)
-            << i.second.hash->printMethodAlgo()
-            << i.second.hash->hash.to_string(Base16, false);
+            << store.printStorePath(i.second.path);
+        if (i.second.hash) {
+            out << i.second.hash->printMethodAlgo()
+                << i.second.hash->hash.to_string(Base16, false);
+        } else {
+            out << "" << "";
+        }
+    }
     writeStorePaths(store, out, drv.inputSrcs);
     out << drv.platform << drv.builder << drv.args;
     out << drv.env.size();
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index c8fcdfed0..01fae3044 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -19,7 +19,7 @@ namespace nix {
 
 void Hash::init()
 {
-    if (!type) abort();
+    assert(type);
     switch (*type) {
     case htMD5: hashSize = md5HashSize; break;
     case htSHA1: hashSize = sha1HashSize; break;
@@ -101,15 +101,15 @@ static string printHash32(const Hash & hash)
 
 string printHash16or32(const Hash & hash)
 {
+    assert(hash.type);
     return hash.to_string(hash.type == htMD5 ? Base16 : Base32, false);
 }
 
 
-HashType assertInitHashType(const Hash & h) {
-    if (h.type)
-        return *h.type;
-    else
-        abort();
+HashType assertInitHashType(const Hash & h)
+{
+    assert(h.type);
+    return *h.type;
 }
 
 std::string Hash::to_string(Base base, bool includeType) const
@@ -363,14 +363,15 @@ HashType parseHashType(const string & s)
 string printHashType(HashType ht)
 {
     switch (ht) {
-    case htMD5: return "md5"; break;
-    case htSHA1: return "sha1"; break;
-    case htSHA256: return "sha256"; break;
-    case htSHA512: return "sha512"; break;
+    case htMD5: return "md5";
+    case htSHA1: return "sha1";
+    case htSHA256: return "sha256";
+    case htSHA512: return "sha512";
+    default:
+        // illegal hash type enum value internally, as opposed to external input
+        // which should be validated with nice error message.
+        abort();
     }
-    // illegal hash type enum value internally, as opposed to external input
-    // which should be validated with nice error message.
-    abort();
 }
 
 }
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index 0d9916508..23259dced 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -10,7 +10,7 @@ namespace nix {
 MakeError(BadHash, Error);
 
 
-enum HashType : char { htMD5, htSHA1, htSHA256, htSHA512 };
+enum HashType : char { htMD5 = 42, htSHA1, htSHA256, htSHA512 };
 
 
 const int md5HashSize = 16;
diff --git a/tests/build-hook.nix b/tests/build-hook.nix
index 8c5ca8cd3..a19c10dde 100644
--- a/tests/build-hook.nix
+++ b/tests/build-hook.nix
@@ -1,23 +1,39 @@
+{ busybox }:
+
 with import ./config.nix;
 
 let
 
+  mkDerivation = args:
+    derivation ({
+      inherit system;
+      builder = busybox;
+      args = ["sh" "-e" args.builder or (builtins.toFile "builder-${args.name}.sh" "if [ -e .attrs.sh ]; then source .attrs.sh; fi; eval \"$buildCommand\"")];
+    } // removeAttrs args ["builder" "meta"])
+    // { meta = args.meta or {}; };
+
   input1 = mkDerivation {
-    name = "build-hook-input-1";
-    buildCommand = "mkdir $out; echo FOO > $out/foo";
+    shell = busybox;
+    name = "build-remote-input-1";
+    buildCommand = "echo FOO > $out";
     requiredSystemFeatures = ["foo"];
   };
 
   input2 = mkDerivation {
-    name = "build-hook-input-2";
-    buildCommand = "mkdir $out; echo BAR > $out/bar";
+    shell = busybox;
+    name = "build-remote-input-2";
+    buildCommand = "echo BAR > $out";
   };
 
 in
 
   mkDerivation {
-    name = "build-hook";
-    builder = ./dependencies.builder0.sh;
-    input1 = " " + input1 + "/.";
-    input2 = " ${input2}/.";
+    shell = busybox;
+    name = "build-remote";
+    buildCommand =
+      ''
+        read x < ${input1}
+        read y < ${input2}
+        echo $x$y > $out
+      '';
   }
diff --git a/tests/build-remote.sh b/tests/build-remote.sh
index a550f4460..4dfb753e1 100644
--- a/tests/build-remote.sh
+++ b/tests/build-remote.sh
@@ -3,22 +3,29 @@ source common.sh
 clearStore
 
 if ! canUseSandbox; then exit; fi
-if [[ ! $SHELL =~ /nix/store ]]; then exit; fi
+if ! [[ $busybox =~ busybox ]]; then exit; fi
 
-chmod -R u+w $TEST_ROOT/store0 || true
-chmod -R u+w $TEST_ROOT/store1 || true
-rm -rf $TEST_ROOT/store0 $TEST_ROOT/store1
+chmod -R u+w $TEST_ROOT/machine0 || true
+chmod -R u+w $TEST_ROOT/machine1 || true
+chmod -R u+w $TEST_ROOT/machine2 || true
+rm -rf $TEST_ROOT/machine0 $TEST_ROOT/machine1 $TEST_ROOT/machine2
+rm -f $TEST_ROOT/result
 
-nix build -f build-hook.nix -o $TEST_ROOT/result --max-jobs 0 \
-  --sandbox-paths /nix/store --sandbox-build-dir /build-tmp \
-  --builders "$TEST_ROOT/store0; $TEST_ROOT/store1 - - 1 1 foo" \
+unset NIX_STORE_DIR
+unset NIX_STATE_DIR
+
+# Note: ssh://localhost bypasses ssh, directly invoking nix-store as a
+# child process. This allows us to test LegacySSHStore::buildDerivation().
+nix build -L -v -f build-hook.nix -o $TEST_ROOT/result --max-jobs 0 \
+  --arg busybox $busybox \
+  --store $TEST_ROOT/machine0 \
+  --builders "ssh://localhost?remote-store=$TEST_ROOT/machine1; $TEST_ROOT/machine2 - - 1 1 foo" \
   --system-features foo
 
-outPath=$TEST_ROOT/result
+outPath=$(readlink -f $TEST_ROOT/result)
 
-cat $outPath/foobar | grep FOOBAR
+cat $TEST_ROOT/machine0/$outPath | grep FOOBAR
 
-# Ensure that input1 was built on store1 due to the required feature.
-p=$(readlink -f $outPath/input-2)
-(! nix path-info --store $TEST_ROOT/store0 --all | grep builder-build-hook-input-1.sh)
-nix path-info --store $TEST_ROOT/store1 --all | grep builder-build-hook-input-1.sh
+# Ensure that input1 was built on store2 due to the required feature.
+(! nix path-info --store $TEST_ROOT/machine1 --all | grep builder-build-remote-input-1.sh)
+nix path-info --store $TEST_ROOT/machine2 --all | grep builder-build-remote-input-1.sh
diff --git a/tests/common.sh.in b/tests/common.sh.in
index dd7e61822..73fe77345 100644
--- a/tests/common.sh.in
+++ b/tests/common.sh.in
@@ -35,6 +35,7 @@ export xmllint="@xmllint@"
 export SHELL="@bash@"
 export PAGER=cat
 export HAVE_SODIUM="@HAVE_SODIUM@"
+export busybox="@sandbox_shell@"
 
 export version=@PACKAGE_VERSION@
 export system=@system@
diff --git a/tests/post-hook.sh b/tests/post-hook.sh
index a02657215..aa3e6a574 100644
--- a/tests/post-hook.sh
+++ b/tests/post-hook.sh
@@ -2,6 +2,8 @@ source common.sh
 
 clearStore
 
+rm -f $TEST_ROOT/result
+
 export REMOTE_STORE=$TEST_ROOT/remote_store
 
 # Build the dependencies and push them to the remote store
diff --git a/tests/recursive.sh b/tests/recursive.sh
index 394ae5ddb..2d4f83895 100644
--- a/tests/recursive.sh
+++ b/tests/recursive.sh
@@ -5,6 +5,8 @@ if [[ $(uname) != Linux ]]; then exit; fi
 
 clearStore
 
+rm -f $TEST_ROOT/result
+
 export unreachable=$(nix add-to-store ./recursive.sh)
 
 nix --experimental-features 'nix-command recursive-nix' build -o $TEST_ROOT/result -L '(
diff --git a/tests/structured-attrs.sh b/tests/structured-attrs.sh
index 646bdb876..dcfe6d580 100644
--- a/tests/structured-attrs.sh
+++ b/tests/structured-attrs.sh
@@ -2,6 +2,8 @@ source common.sh
 
 clearStore
 
+rm -f $TEST_ROOT/result
+
 nix-build structured-attrs.nix -A all -o $TEST_ROOT/result
 
 [[ $(cat $TEST_ROOT/result/foo) = bar ]]