diff --git a/flake.nix b/flake.nix
index 3823004..594f16b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -39,8 +39,8 @@
           ./testing/elems.test.nix
           ./testing/site.test.nix
           ./testing/style.test.nix
+          ./testing/builder.test.nix
         ];
-
       };
     };
 }
diff --git a/nixite/builder.nix b/nixite/builder.nix
new file mode 100644
index 0000000..c709154
--- /dev/null
+++ b/nixite/builder.nix
@@ -0,0 +1,26 @@
+rec {
+  buildSiteTo = prefix: site:
+    builtins.toString (builtins.attrValues (builtins.mapAttrs (name: content:
+      if builtins.isString content
+      then ''
+        cp ${builtins.toFile name content} ${prefix}/${name}
+      ''
+      else if builtins.isPath content
+      then ''
+        cp -r ${content} ${prefix}/${name}
+      ''
+      else if builtins.isAttrs content && content ? "__toString"
+      then ''
+        cp ${builtins.toFile name (toString content)} ${prefix}/${name}
+      ''
+      else if builtins.isAttrs content
+      then ''
+        mkdir -p ${prefix}/${name}
+        ${buildSiteTo "${prefix}/${name}" content}
+      ''
+      else
+        throw "Site page must be string, path or attrset, but got ${
+          builtins.typeOf content
+        }: [${toString content}]")
+    site));
+}
diff --git a/nixite/make-site.nix b/nixite/make-site.nix
index 3730a78..e3e5092 100644
--- a/nixite/make-site.nix
+++ b/nixite/make-site.nix
@@ -1,28 +1,5 @@
 pkgs: raw: let
-  buildSiteTo = prefix: site:
-    builtins.toString (builtins.attrValues (builtins.mapAttrs (name: content:
-      if builtins.isString content
-      then ''
-        cp ${builtins.toFile name content} ${prefix}/${name}
-      ''
-      else if builtins.isPath content
-      then ''
-        cp -r ${content} ${prefix}/${name}
-      ''
-      else if builtins.isAttrs content && content ? "__toString"
-      then ''
-        cp ${builtins.toFile name (toString content)} ${prefix}/${name}
-      ''
-      else if builtins.isAttrs content
-      then ''
-        mkdir -p ${prefix}/${name}
-        ${buildSiteTo "${prefix}/${name}" content}
-      ''
-      else
-        throw "Site page must be string, path or attrset, but got ${
-          builtins.typeOf content
-        }: [${toString content}]")
-    site));
+  builder = import ./builder.nix;
 in
   derivation {
     builder = "/bin/sh";
@@ -33,7 +10,7 @@ in
       ''
         PATH=$PATH:${pkgs.coreutils}/bin
         mkdir $out
-        ${buildSiteTo "$out" raw}
+        ${builder.buildSiteTo "$out" raw}
       ''
     ];
   }
diff --git a/nixite/serve.nix b/nixite/serve.nix
index 5b425bd..d2f241c 100644
--- a/nixite/serve.nix
+++ b/nixite/serve.nix
@@ -24,5 +24,4 @@ in
         chmod +x $out/bin/nixite-server
       ''
     ];
-    inherit my-site;
   }
diff --git a/testing/builder.test.nix b/testing/builder.test.nix
new file mode 100644
index 0000000..b54c062
--- /dev/null
+++ b/testing/builder.test.nix
@@ -0,0 +1,47 @@
+{
+  describe,
+  it,
+  ...
+}: let
+  builder = import ../nixite/builder.nix;
+in
+  with builder; [
+    (describe "buildSiteTo" [
+      (it "copies all the files" {
+        actual = buildSiteTo "." {
+          page = "this is a page";
+          subdir = {
+            page = "this page is in a subdir";
+            link = ./src;
+          };
+        };
+        expected = ''
+          cp /nix/store/crirfz0n6f8dgl1si3x7pwyw7fqm0r8l-page ./page
+           mkdir -p ./subdir
+          cp -r /nix/store/q95cn7ccixzi9w22aic4bl0ykk40ka7v-src ./subdir/link
+           cp /nix/store/ic6fyy8wg8r4338a3m5kinmg11igxsyj-page ./subdir/page
+
+        '';
+      })
+
+      (it "throws with a list for a page" {
+        actual = buildSiteTo "." {page = [];};
+        throws = true;
+      })
+
+      (it "throws with null for a page" {
+        actual = buildSiteTo "." {page = null;};
+        throws = true;
+      })
+
+      (it "throws with a bool for a page" {
+        actual = buildSiteTo "." {page = true;};
+        throws = true;
+      })
+
+      (it "throws with a number for a page" {
+        actual = buildSiteTo "." {page = 5;};
+        throws = true;
+      })
+    ])
+  ]
diff --git a/testing/site.test.nix b/testing/site.test.nix
index e7dca66..0faebf8 100644
--- a/testing/site.test.nix
+++ b/testing/site.test.nix
@@ -235,44 +235,6 @@ in
         };
       }))
     ])
-    (describe "copyTo" [
-      (it "copies all the files" {
-        actual = copyTo "." {
-          page = "this is a page";
-          subdir = {
-            page = "this page is in a subdir";
-            link = ./src;
-          };
-        };
-        expected = ''
-          cp /nix/store/crirfz0n6f8dgl1si3x7pwyw7fqm0r8l-page ./page
-           mkdir -p ./subdir
-          cp -r /nix/store/q95cn7ccixzi9w22aic4bl0ykk40ka7v-src ./subdir/link
-           cp /nix/store/ic6fyy8wg8r4338a3m5kinmg11igxsyj-page ./subdir/page
-
-        '';
-      })
-
-      (it "throws with a list for a page" {
-        actual = copyTo "." {page = [];};
-        throws = true;
-      })
-
-      (it "throws with null for a page" {
-        actual = copyTo "." {page = null;};
-        throws = true;
-      })
-
-      (it "throws with a bool for a page" {
-        actual = copyTo "." {page = true;};
-        throws = true;
-      })
-
-      (it "throws with a number for a page" {
-        actual = copyTo "." {page = 5;};
-        throws = true;
-      })
-    ])
     (describe "prepare" [
       (it "prepares the site" {
         actual = prepare {favicon = ./src/favicon.png;} my-site;