diff --git a/php-mode-test.el b/php-mode-test.el
index 654ddddd..ac9973fb 100644
--- a/php-mode-test.el
+++ b/php-mode-test.el
@@ -721,7 +721,12 @@ style from Drupal."
     (search-forward "SpaceName")
     (goto-char (match-beginning 0))
     (should (eq 'php-constant
-                (get-text-property (point) 'face)))))
+                (get-text-property (point) 'face)))
+    (search-forward-regexp "\\\\My_\\(Class\\)")
+    (should (eq 'php-constant
+                (get-text-property (match-beginning 0) 'face)))
+    (should (eq 'php-constant
+                (get-text-property (match-beginning 1) 'face)))))
 
 (ert-deftest php-mode-test-variables()
   "Proper highlighting for variables."
diff --git a/php-mode.el b/php-mode.el
index 9bb3a1ee..6b7074a1 100644
--- a/php-mode.el
+++ b/php-mode.el
@@ -1565,8 +1565,8 @@ a completion list."
      (")\\s-*:\\s-*\\??\\(array\\)\\b" 1 font-lock-type-face)
 
      ;; namespaces
-     ("\\(\\([a-zA-Z0-9]+\\\\\\)+[a-zA-Z0-9]+\\|\\(\\\\[a-zA-Z0-9]+\\)+\\)[^:a-zA-Z0-9\\\\]" 1 'font-lock-type-face)
-     ("\\(\\([a-zA-Z0-9]+\\\\\\)+[a-zA-Z0-9]+\\|\\(\\\\[a-zA-Z0-9]+\\)+\\)::" 1 'php-constant)
+     ("\\(\\([a-zA-Z0-9_]+\\\\\\)+[a-zA-Z0-9_]+\\|\\(\\\\[a-zA-Z0-9_]+\\)+\\)[^:a-zA-Z0-9_\\\\]" 1 'font-lock-type-face)
+     ("\\(\\([a-zA-Z0-9_]+\\\\\\)+[a-zA-Z0-9_]+\\|\\(\\\\[a-zA-Z0-9_]+\\)+\\)::" 1 'php-constant)
 
      ;; Support the ::class constant in PHP5.6
      ("\\sw+\\(::\\)\\(class\\)\\b" (1 'php-paamayim-nekudotayim) (2 'php-constant)))
diff --git a/tests/identifiers.php b/tests/identifiers.php
index ed0a6a6a..06299cd5 100644
--- a/tests/identifiers.php
+++ b/tests/identifiers.php
@@ -12,4 +12,5 @@
 // When calling a method, the class name should be highlighted with
 // the constant face. Just like c++-mode "NS::Class::method()"
 ClassName::method();
-\SpaceName\ClassName::method();
\ No newline at end of file
+\SpaceName\ClassName::method();
+\My_Class::method();