diff --git a/gulpfile.js b/gulpfile.js
index cea77ecef..59627597c 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -1159,7 +1159,7 @@ function buildLib(defines, dir) {
   // require with __webpack_require__. When we want to use the real require,
   // __non_webpack_require__ has to be used.
   // In this target, we don't create a bundle, so we have to replace the
-  // occurences of __non_webpack_require__ ourselves.
+  // occurrences of __non_webpack_require__ ourselves.
   function babelPluginReplaceNonWebPackRequire(babel) {
     return {
       visitor: {
diff --git a/systemjs.config.js b/systemjs.config.js
index be9199781..c5d8185aa 100644
--- a/systemjs.config.js
+++ b/systemjs.config.js
@@ -44,7 +44,7 @@
   // require with __webpack_require__. When we want to use the real require,
   // __non_webpack_require__ has to be used.
   // In this target, we don't create a bundle, so we have to replace the
-  // occurences of __non_webpack_require__ ourselves.
+  // occurrences of __non_webpack_require__ ourselves.
   function babelPluginReplaceNonWebPackRequire(babel) {
     return {
       visitor: {