diff --git a/php-mode.el b/php-mode.el
index 31fbd65e..5a374559 100644
--- a/php-mode.el
+++ b/php-mode.el
@@ -472,7 +472,7 @@ In that case set to `NIL'."
 
 (c-lang-defconst c-primitive-type-kwds
   php '("int" "integer" "bool" "boolean" "float" "double" "real"
-        "string" "object" "void"))
+        "string" "object" "void" "mixed"))
 
 (c-lang-defconst c-class-decl-kwds
   "Keywords introducing declarations where the following block (if any)
diff --git a/tests/lang/types/keywords.php b/tests/lang/types/keywords.php
index fc1b4f66..e9ba7785 100644
--- a/tests/lang/types/keywords.php
+++ b/tests/lang/types/keywords.php
@@ -12,3 +12,4 @@
 string;
 object;
 resource;
+mixed;