diff --git a/lib/middleman-gh-pages/tasks/gh-pages.rake b/lib/middleman-gh-pages/tasks/gh-pages.rake
index 7c13644..c455104 100644
--- a/lib/middleman-gh-pages/tasks/gh-pages.rake
+++ b/lib/middleman-gh-pages/tasks/gh-pages.rake
@@ -1,4 +1,5 @@
 require 'fileutils'
+require 'tmpdir'
 
 def remote_name
   ENV.fetch("REMOTE_NAME", "origin")
@@ -12,6 +13,15 @@ def nothing_to_commit?
   `git status --porcelain`.chomp.empty?
 end
 
+def backup_and_restore(dir, file, &block)
+  yield unless File.exist?(File.join(dir, file))
+  Dir.mktmpdir do |tmpdir|
+    mv File.join(dir, file), tmpdir
+    yield
+    mv File.join(tmpdir, file), dir
+  end
+end
+
 PROJECT_ROOT = `git rev-parse --show-toplevel`.strip
 BUILD_DIR    = File.join(PROJECT_ROOT, "build")
 GH_PAGES_REF = File.join(BUILD_DIR, ".git/refs/remotes/#{remote_name}/#{branch_name}")
@@ -65,8 +75,10 @@ end
 
 desc "Compile all files into the build directory"
 task :build do
-  cd PROJECT_ROOT do
-    sh "bundle exec middleman build --clean"
+  backup_and_restore(BUILD_DIR, ".git") do
+    cd PROJECT_ROOT do
+      sh "bundle exec middleman build --clean"
+    end
   end
 end