diff --git a/.gitignore b/.gitignore
index 4f2489d..e97481a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,5 +18,6 @@
 /vendor/
 /Godeps/
 
-# Sitemap file
+# Sitemap files
+previous-sitemap.md
 sitemap.md
diff --git a/main.go b/main.go
index 5e84837..de14219 100644
--- a/main.go
+++ b/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"sort"
 	"strings"
@@ -18,6 +19,13 @@ type wikiPage struct {
 
 func main() {
 	log.Infof("Tildes Wiki Sitemap\n")
+	// Create a variable we'll use to check if a current sitemap already exists
+	_, sitemapExists := os.Stat("sitemap.md")
+	if sitemapExists == nil {
+		// If it does exist, rename it to "previous"
+		os.Rename("sitemap.md", "previous-sitemap.md")
+	}
+
 	// Create a groups array, which will be used to sort the output
 	// (couldn't figure out how to sort a map by keys)
 	groups := make([]string, 0)
@@ -106,5 +114,31 @@ func main() {
 
 	// And finally write how many groups and pages there are, like `tree` writes directories and files
 	file.WriteString(fmt.Sprintf("\n%v groups, %v pages\n", len(groups), pagesTotal))
+
+	// If the sitemap exists we want to read both sitemaps and check if they're the same
+	if sitemapExists == nil {
+		file, err := os.Open("sitemap.md")
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		current, _ := ioutil.ReadAll(file)
+		file.Close()
+		file, err = os.Open("previous-sitemap.md")
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		previous, _ := ioutil.ReadAll(file)
+		file.Close()
+
+		// If they're the same just log that all is good, if not warn that we need to update
+		if string(current) == string(previous) {
+			log.Infof("Current and previous sitemaps are the same, no need to update.\n")
+		} else {
+			log.Warnf("Current and previous sitemaps are not the same, you should update it.\n")
+		}
+	}
+
 	log.Printf("Done! Found %v groups and %v pages, see sitemap.md for the output", len(groups), pagesTotal)
 }