diff --git a/core/includes/file.inc b/core/includes/file.inc
index 034a997459d..79914af51c9 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -1110,32 +1110,6 @@ function file_upload_max_size() {
   return $max_size;
 }
 
-/**
- * Determines an Internet Media Type or MIME type from a filename.
- *
- * @param $uri
- *   A string containing the URI, path, or filename.
- * @param $mapping
- *   An optional map of extensions to their mimetypes, in the form:
- *    - 'mimetypes': a list of mimetypes, keyed by an identifier,
- *    - 'extensions': the mapping itself, an associative array in which the key
- *      is the extension (lowercase) and the value is the mimetype identifier.
- *
- * @return
- *   The internet media type registered for the extension or
- *   application/octet-stream for unknown extensions.
- *
- * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0. Calls are
- *   passed on to a new file.mime_type.guesser service, and the $mapping
- *   parameter is ignored. Use
- *   \Drupal::service('file.mime_type.guesser')->guess($uri).
- *
- * @see \Drupal\Core\File\MimeType\ExtensionMimeTypeGuesser::guess()
- */
-function file_get_mimetype($uri, $mapping = NULL) {
-  return \Drupal::service('file.mime_type.guesser')->guess($uri);
-}
-
 /**
  * Sets the permissions on a file or directory.
  *