diff --git a/php/src/ref/schema/ref_types.php b/php/src/ref/schema/ref_types.php
index 24973d5..d7ce1d4 100644
--- a/php/src/ref/schema/ref_types.php
+++ b/php/src/ref/schema/ref_types.php
@@ -6,5 +6,6 @@ class ref_types {
     "boolean" => "bool",
     "integer" => "int",
     "flt" => "float", "double" => "float", "dbl" => "float",
+    "func" => "callable", "function" => "callable",
   ];
 }