keyword-params ignores parameters that cannot be keywords

@@ -1,11 +1,14 @@
 (ns ring.middleware.keyword-params
   "Convert param keys to keywords.")
 
+(defn- keyword-syntax? [s]
+  (re-matches #"[A-Za-z*+!_?-][A-Za-z0-9*+!_?-]*" s))
+
 (defn- keyify-params [target]
   (cond
     (map? target)
       (into {}
-        (for [[k v] target]
+        (for [[k v] target :when (keyword-syntax? k)]
           [(keyword k) (keyify-params v)]))
     (vector? target)
       (vec (map keyify-params target))

@@ -11,4 +11,6 @@
     {"foo" "bar" "biz" [{"bat" "one"} {"bat" "two"}]}
     {:foo  "bar" :biz  [{:bat "one"}  {:bat  "two"}]}
     {"foo" 1}
-    {:foo  1}))
+    {:foo  1}
+    {"foo" 1 "1bar" 2 "baz*" 3 "quz-buz" 4 "biz.bang" 5}
+    {:foo 1 :baz* 3 :quz-buz 4}))