diff --git a/src/libutil/archive.cc b/src/libutil/archive.cc
index 268a798d9..0f0cae7c0 100644
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -27,8 +27,6 @@ struct ArchiveSettings : Config
         #endif
         "use-case-hack",
         "Whether to enable a Darwin-specific hack for dealing with file name collisions."};
-    Setting<bool> preallocateContents{this, false, "preallocate-contents",
-        "Whether to preallocate files when writing objects with known size."};
 };
 
 static ArchiveSettings archiveSettings;
@@ -302,71 +300,6 @@ void parseDump(ParseSink & sink, Source & source)
 }
 
 
-struct RestoreSink : ParseSink
-{
-    Path dstPath;
-    AutoCloseFD fd;
-
-    void createDirectory(const Path & path) override
-    {
-        Path p = dstPath + path;
-        if (mkdir(p.c_str(), 0777) == -1)
-            throw SysError("creating directory '%1%'", p);
-    };
-
-    void createRegularFile(const Path & path) override
-    {
-        Path p = dstPath + path;
-        fd = open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0666);
-        if (!fd) throw SysError("creating file '%1%'", p);
-    }
-
-    void closeRegularFile() override
-    {
-        /* Call close explicitly to make sure the error is checked */
-        fd.close();
-    }
-
-    void isExecutable() override
-    {
-        struct stat st;
-        if (fstat(fd.get(), &st) == -1)
-            throw SysError("fstat");
-        if (fchmod(fd.get(), st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
-            throw SysError("fchmod");
-    }
-
-    void preallocateContents(uint64_t len) override
-    {
-        if (!archiveSettings.preallocateContents)
-            return;
-
-#if HAVE_POSIX_FALLOCATE
-        if (len) {
-            errno = posix_fallocate(fd.get(), 0, len);
-            /* Note that EINVAL may indicate that the underlying
-               filesystem doesn't support preallocation (e.g. on
-               OpenSolaris).  Since preallocation is just an
-               optimisation, ignore it. */
-            if (errno && errno != EINVAL && errno != EOPNOTSUPP && errno != ENOSYS)
-                throw SysError("preallocating file of %1% bytes", len);
-        }
-#endif
-    }
-
-    void receiveContents(std::string_view data) override
-    {
-        writeFull(fd.get(), data);
-    }
-
-    void createSymlink(const Path & path, const std::string & target) override
-    {
-        Path p = dstPath + path;
-        nix::createSymlink(target, p);
-    }
-};
-
-
 void restorePath(const Path & path, Source & source)
 {
     RestoreSink sink;
diff --git a/src/libutil/fs-sink.cc b/src/libutil/fs-sink.cc
new file mode 100644
index 000000000..fcffd3216
--- /dev/null
+++ b/src/libutil/fs-sink.cc
@@ -0,0 +1,82 @@
+#include <fcntl.h>
+
+#include "config.hh"
+#include "fs-sink.hh"
+
+namespace nix {
+
+struct RestoreSinkSettings : Config
+{
+    Setting<bool> preallocateContents{this, false, "preallocate-contents",
+        "Whether to preallocate files when writing objects with known size."};
+};
+
+static RestoreSinkSettings restoreSinkSettings;
+
+static GlobalConfig::Register r1(&restoreSinkSettings);
+
+struct RestoreSink : ParseSink
+{
+    Path dstPath;
+    AutoCloseFD fd;
+
+    void createDirectory(const Path & path) override
+    {
+        Path p = dstPath + path;
+        if (mkdir(p.c_str(), 0777) == -1)
+            throw SysError("creating directory '%1%'", p);
+    };
+
+    void createRegularFile(const Path & path) override
+    {
+        Path p = dstPath + path;
+        fd = open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0666);
+        if (!fd) throw SysError("creating file '%1%'", p);
+    }
+
+    void closeRegularFile() override
+    {
+        /* Call close explicitly to make sure the error is checked */
+        fd.close();
+    }
+
+    void isExecutable() override
+    {
+        struct stat st;
+        if (fstat(fd.get(), &st) == -1)
+            throw SysError("fstat");
+        if (fchmod(fd.get(), st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
+            throw SysError("fchmod");
+    }
+
+    void preallocateContents(uint64_t len) override
+    {
+        if (!archiveSettings.preallocateContents)
+            return;
+
+#if HAVE_POSIX_FALLOCATE
+        if (len) {
+            errno = posix_fallocate(fd.get(), 0, len);
+            /* Note that EINVAL may indicate that the underlying
+               filesystem doesn't support preallocation (e.g. on
+               OpenSolaris).  Since preallocation is just an
+               optimisation, ignore it. */
+            if (errno && errno != EINVAL && errno != EOPNOTSUPP && errno != ENOSYS)
+                throw SysError("preallocating file of %1% bytes", len);
+        }
+#endif
+    }
+
+    void receiveContents(std::string_view data) override
+    {
+        writeFull(fd.get(), data);
+    }
+
+    void createSymlink(const Path & path, const std::string & target) override
+    {
+        Path p = dstPath + path;
+        nix::createSymlink(target, p);
+    }
+};
+
+}