diff --git a/system/helpers/file_helper.php b/system/helpers/file_helper.php
index 0d7b5d5..cb3d60e 100644
--- a/system/helpers/file_helper.php
+++ b/system/helpers/file_helper.php
@@ -340,7 +340,7 @@
 {
 	function get_mime_by_extension($file)
 	{
-		$extension = substr(strrchr($file, '.'), 1);
+		$extension = strtolower(substr(strrchr($file, '.'), 1));
 
 		global $mimes;
 
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index a6eaef1..a941904 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -78,6 +78,7 @@
 <ul>
 	<li>Increased randomness with<kbd>is_really_writable()</kbd> to avoid file collisions when hundreds or thousands of requests occur at once.</li>
 	<li>Fixed or clarified assorted user guide typos or examples.</li>
+	<li>Made <kbd>get_mime_by_extension()</kbd> case insensitive.</li>
 </ul>
 
 <h2>Version 1.7.2</h2>