diff --git a/CHANGELOG.md b/CHANGELOG.md
index a0b2f7d4..e685f348 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@
 * [#429](https://github.com/clojure-emacs/clojure-mode/issues/429): Fix a bug causing last occurrence of expression sometimes is not replaced when using `move-to-let`.
 * [#423](https://github.com/clojure-emacs/clojure-mode/issues/423): Make `clojure-match-next-def` more robust against zero-arity def-like forms.
 * [#451](https://github.com/clojure-emacs/clojure-mode/issues/451): Make project root directory calculation customized by `clojure-project-root-function`.
+* Fix namespace font-locking.
 
 ## 5.6.1 (2016-12-21)
 
diff --git a/clojure-mode.el b/clojure-mode.el
index f1421f0a..ab69a039 100644
--- a/clojure-mode.el
+++ b/clojure-mode.el
@@ -855,19 +855,19 @@ any number of matches of `clojure--sym-forbidden-rest-chars'."))
       ;; Java interop highlighting
       ;; CONST SOME_CONST (optionally prefixed by /)
       ("\\(?:\\<\\|/\\)\\([A-Z]+\\|\\([A-Z]+_[A-Z1-9_]+\\)\\)\\>" 1 font-lock-constant-face)
+      ;; special handling for foo.bar.baz in the namespace definition
+      (,(concat "(\\<ns\\>[ \r\n\t]*"
+                ;; Possibly metadata
+                "\\(?:\\^?{[^}]+}[ \r\n\t]*\\)*"
+                ;; namespace
+                "\\(" clojure--sym-regexp "\\)")
+       (1 font-lock-type-face nil t))
       ;; .foo .barBaz .qux01 .-flibble .-flibbleWobble
       ("\\<\\.-?[a-z][a-zA-Z0-9]*\\>" 0 'clojure-interop-method-face)
       ;; Foo Bar$Baz Qux_ World_OpenUDP Foo. Babylon15.
       ("\\(?:\\<\\|\\.\\|/\\|#?^\\)\\([A-Z][a-zA-Z0-9_]*[a-zA-Z0-9$_]+\\.?\\>\\)" 1 font-lock-type-face)
       ;; foo.bar.baz
       ("\\<^?\\([a-z][a-z0-9_-]+\\.\\([a-z][a-z0-9_-]*\\.?\\)+\\)" 1 font-lock-type-face)
-      ;; (ns namespace) - special handling for single segment namespaces
-      (,(concat "(\\<ns\\>[ \r\n\t]*"
-                ;; Possibly metadata
-                "\\(?:\\^?{[^}]+}[ \r\n\t]*\\)*"
-                ;; namespace
-                "\\([a-z0-9-]+\\)")
-       (1 font-lock-type-face nil t))
       ;; fooBar
       ("\\(?:\\<\\|/\\)\\([a-z]+[A-Z]+[a-zA-Z0-9$]*\\>\\)" 1 'clojure-interop-method-face)
       ;; #_ and (comment ...) macros.
diff --git a/test.clj b/test.clj
index 06b519fe..f1e2db1a 100644
--- a/test.clj
+++ b/test.clj
@@ -1,7 +1,29 @@
 ;;; font locking
 (ns clojure-mode.demo
-  (:require [clojure.something]
-            [something.s]))
+  (:require
+   [clojure.something]
+   [something.s]
+   [oneword]
+   ;; TODO mixedCase shouldn't be font-locked to clojure-interop-method-face
+   [mixedCase]
+   [CamelCase]))
+
+;; examples of valid namespace definitions
+(comment
+  (ns .validns)
+  (ns =validns)
+  (ns .ValidNs=<>?+|?*.)
+  (ns ValidNs<>?+|?*.b*ar.ba*z)
+  (ns other.valid.ns)
+  (ns oneword)
+  (ns one.X)
+  (ns foo.bar)
+  (ns Foo.bar)
+  (ns Foo.Bar)
+  (ns foo.Bar)
+  (ns Foo-bar)
+  (ns Foo-Bar)
+  (ns foo-Bar))
 
 (comment ;; for indentation
   (with-hi heya
diff --git a/test/clojure-mode-font-lock-test.el b/test/clojure-mode-font-lock-test.el
index 8e5d0bda..50493915 100644
--- a/test/clojure-mode-font-lock-test.el
+++ b/test/clojure-mode-font-lock-test.el
@@ -162,6 +162,23 @@ POS."
     (should (eq (clojure-test-face-at 5 14) 'font-lock-type-face))))
 
 (ert-deftest clojure-mode-syntax-table/namespace ()
+  :tags '(fontification syntax-table)
+  (should (eq (clojure-test-face-at 5 12 "(ns .validns)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 12 "(ns =validns)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 21 "(ns .ValidNs=<>?+|?*.)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 28 "(ns ValidNs<>?+|?*.b*ar.ba*z)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 18 "(ns other.valid.ns)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns oneword)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns foo.bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns Foo.bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns Foo.Bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns foo.Bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns Foo-bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns Foo-Bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 11 "(ns foo-Bar)") 'font-lock-type-face))
+  (should (eq (clojure-test-face-at 5 9 "(ns one.X)") 'font-lock-type-face)))
+
+(ert-deftest clojure-mode-syntax-table/segmented-symbol ()
   :tags '(fontification syntax-table)
   (should (eq (clojure-test-face-at 1 5 "one.p") 'font-lock-type-face))
   (should (eq (clojure-test-face-at 1 11 "one.p.top13") 'font-lock-type-face))