diff --git a/core/modules/php/php.module b/core/modules/php/php.module
index 4c68abe..a30c607 100644
--- a/core/modules/php/php.module
+++ b/core/modules/php/php.module
@@ -36,7 +36,7 @@ function php_permission() {
 }
 
 /**
- * Implements hook_filter_FILTER_process().
+ * Evaluates a string of PHP code.
  *
  * This is a wrapper around PHP's eval(). It uses output buffering to capture
  * both returned and printed text. Unlike eval(), we require code to be
@@ -46,6 +46,9 @@ function php_permission() {
  * Using this wrapper also ensures that the PHP code which is evaluated can not
  * overwrite any variables in the calling code, unlike a regular eval() call.
  *
+ * This function is also used as an implementation of
+ * hook_filter_FILTER_process().
+ *
  * @param $code
  *   The code to evaluate.
  *