diff --git a/src/backends/backend.js b/src/backends/backend.js
index 19d02097..96746a0d 100644
--- a/src/backends/backend.js
+++ b/src/backends/backend.js
@@ -5,8 +5,7 @@ import GitGatewayBackend from "./git-gateway/implementation";
 import { resolveFormat } from "../formats/formats";
 import { selectListMethod, selectEntrySlug, selectEntryPath, selectAllowNewEntries, selectFolderEntryExtension } from "../reducers/collections";
 import { createEntry } from "../valueObjects/Entry";
-import { sanitizeIRI } from "../lib/urlHelper";
-import sanitizeFilename from 'sanitize-filename';
+import { sanitizeSlug } from "../lib/urlHelper";
 
 class LocalStorageAuthStore {
   storageKey = "netlify-cms-user";
@@ -43,7 +42,7 @@ const slugFormatter = (template = "{{slug}}", entryData) => {
     return identifier;
   };
 
-  let slug = template.replace(/\{\{([^\}]+)\}\}/g, (_, field) => {
+  const slug = template.replace(/\{\{([^\}]+)\}\}/g, (_, field) => {
     switch (field) {
       case "year":
         return date.getFullYear();
@@ -56,21 +55,14 @@ const slugFormatter = (template = "{{slug}}", entryData) => {
       default:
         return entryData.get(field, "").trim();
     }
-  });
-
-  // Convert slug to lower-case;
-  slug = slug.toLocaleLowerCase();
+  })
+  // Convert slug to lower-case
+  .toLocaleLowerCase()
 
   // Replace periods and spaces with dashes.
-  slug = slug.replace(/[.\s]/g, '-');
-  // Sanitize as IRI (i18n URI) and as filename.
-  slug = sanitizeIRI(slug, {replacement: "-"});
-  slug = sanitizeFilename(slug, {replacement: "-"});
+  .replace(/[.\s]/g, '-');
 
-  // Remove any doubled or trailing replacement characters (that were added in the sanitizers).
-  slug = slug.replace(/-+/g, '-').replace(/-$/, '');
-
-  return slug;
+  return sanitizeSlug(slug);
 };
 
 class Backend {
diff --git a/src/lib/urlHelper.js b/src/lib/urlHelper.js
index 63dff30c..da81ec7e 100644
--- a/src/lib/urlHelper.js
+++ b/src/lib/urlHelper.js
@@ -1,4 +1,6 @@
 import url from 'url';
+import sanitizeFilename from 'sanitize-filename';
+import { isString, escapeRegExp } from 'lodash';
 
 function getUrl(url, direct) {
   return `${ direct ? '/#' : '' }${ url }`;
@@ -28,6 +30,23 @@ export function sanitizeIRI(str, { replacement }) {
   return result;
 }
 
+export function sanitizeSlug(str, { replacement = '-' }) {
+  if (!isString(str)) throw "`sanitizeSlug` only accepts strings as input.";
+  if (!isString(replacement)) throw "the `sanitizeSlug` replacement character must be a string.";
+  let slug = str;
+
+  // Sanitize as IRI (i18n URI) and as filename.
+  slug = sanitizeIRI(slug, {replacement});
+  slug = sanitizeFilename(slug, {replacement});
+
+  // Remove any doubled or trailing replacement characters (that were added in the sanitizers).
+  const doubleReplacement = new RegExp('(?:' + escapeRegExp(replacement) + ')+', 'g');
+  const trailingReplacment = new RegExp(escapeRegExp(replacement) + '$')
+  slug = slug.replace(doubleReplacement, '-').replace(trailingReplacment, '');
+
+  return slug;
+}
+
 export function urlize(string) {
   const sanitized = makePathSanitized(string);
   const parsedURL = url.parse(sanitized);