diff --git a/diff.api.php b/diff.api.php
index 507293a..38515d3 100644
--- a/diff.api.php
+++ b/diff.api.php
@@ -177,5 +177,18 @@ function hook_field_diff_view_alter($values, $items, $context) {
 }
 
 /**
+ * Allow other modules to alter the diff header.
+ *
+ * @param array $header
+ *   The header array for a diff view.
+ * @param stdClass $old_node
+ *   The "left" node on the diff.
+ * @param stdClass $new_node
+ *   The "right" node on the diff.
+ */
+function hook_diff_header_alter(&$header, $old_node, $new_node) {
+}
+
+/**
  * @} End of "addtogroup hooks".
  */
diff --git a/diff.pages.inc b/diff.pages.inc
index 1cd1441..6e81ff5 100644
--- a/diff.pages.inc
+++ b/diff.pages.inc
@@ -208,6 +208,7 @@ function diff_diffs_show($node, $old_vid, $new_vid, $state = NULL) {
   }
 
   $header = _diff_default_header($old_header, $new_header);
+  drupal_alter('diff_header', $header, $old_node, $new_node);
   $rows = array();
   if ($old_log || $new_log) {
     $rows['logs'] = array(