diff --git a/README.md b/README.md
index 3942e1e..76e3990 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 Current [semantic](http://semver.org/) version:
 
 ```clojure
-[com.taoensso/timbre "0.8.2"]
+[com.taoensso/timbre "0.8.3"]
 ```
 
 **Breaking changes** since _0.7.x_:
@@ -35,7 +35,7 @@ Timbre is an attempt to make **simple logging simple** and more **complex loggin
 Timbre is still currently *experimental*. It **has not yet been thoroughly tested in production** and its API is subject to change. To run tests against all supported Clojure versions, use:
 
 ```bash
-lein2 all test
+lein all test
 ```
 
 ## Getting Started
@@ -45,7 +45,7 @@ lein2 all test
 Depend on Timbre in your `project.clj`:
 
 ```clojure
-[com.taoensso/timbre "0.8.2"]
+[com.taoensso/timbre "0.8.3"]
 ```
 
 and `use` the library:
@@ -255,4 +255,4 @@ I'm also on Twitter: [@ptaoussanis](https://twitter.com/#!/ptaoussanis).
 
 Copyright © 2012 Peter Taoussanis
 
-Distributed under the [Eclipse Public License](http://www.eclipse.org/legal/epl-v10.html), the same as Clojure.
\ No newline at end of file
+Distributed under the [Eclipse Public License](http://www.eclipse.org/legal/epl-v10.html), the same as Clojure.
diff --git a/project.clj b/project.clj
index de487ee..584d9d2 100644
--- a/project.clj
+++ b/project.clj
@@ -1,4 +1,4 @@
-(defproject com.taoensso/timbre "0.8.2"
+(defproject com.taoensso/timbre "0.8.3"
   :description "Simple, flexible, all-Clojure logging. No XML!"
   :url "https://github.com/ptaoussanis/timbre"
   :license {:name "Eclipse Public License"}
diff --git a/src/taoensso/timbre.clj b/src/taoensso/timbre.clj
index 99a5c9d..6092330 100644
--- a/src/taoensso/timbre.clj
+++ b/src/taoensso/timbre.clj
@@ -81,15 +81,16 @@
 ;;;; Define and sort logging levels
 
 (def ^:private ordered-levels [:trace :debug :info :warn :error :fatal :report])
-(def ^:private scored-levels  (zipmap ordered-levels (range)))
-(defn assert-valid-level
-  [x] (when-not (some #{x} ordered-levels)
-        (throw (Exception. (str "Invalid logging level: " x)))))
+(def ^:private scored-levels  (assoc (zipmap ordered-levels (range)) nil 0))
 
-(defn error-level? [x] (boolean (#{:error :fatal} x)))
+(defn error-level? [level] (boolean (#{:error :fatal} level)))
+
+(defn- checked-level-score [level]
+  (or (scored-levels level)
+      (throw (Exception. (str "Invalid logging level: " level)))))
 
 (def compare-levels
-  (memoize (fn [x y] (- (scored-levels x) (scored-levels y)))))
+  (memoize (fn [x y] (- (checked-level-score x) (checked-level-score y)))))
 
 (defn sufficient-level?
   [level] (>= (compare-levels level (:current-level @config)) 0))
@@ -179,8 +180,7 @@
   [level]
   (->> (:appenders @config)
        (filter #(let [{:keys [enabled? min-level]} (val %)]
-                  (and enabled? (or (nil? min-level)
-                                    (>= (compare-levels level min-level) 0)))))
+                  (and enabled? (>= (compare-levels level min-level) 0))))
        (into {})))
 
 (comment (relevant-appenders :debug)
@@ -241,14 +241,12 @@
   "Returns true when current logging level is sufficient and current namespace
   is unfiltered."
   [level]
-  (assert-valid-level level)
   `(and (sufficient-level? ~level) (@ns-filter-cache ~*ns*)))
 
 (defmacro log*
   "Prepares given arguments for, and then dispatches to all relevant
   appender-fns."
   [level base-args & sigs]
-  (assert-valid-level level)
   `(when-let [juxt-fn# (@appenders-juxt-cache ~level)] ; Any relevant appenders?
      (let [[x1# & xs#] (list ~@sigs)
 
@@ -274,7 +272,6 @@
   appender-fns. Generic form of standard level-loggers (trace, info, etc.)."
   {:arglists '([level message & more] [level throwable message & more])}
   [level & sigs]
-  (assert-valid-level level)
   `(when (logging-enabled? ~level)
      (log* ~level {} ~@sigs)))
 
@@ -313,6 +310,8 @@
   (log :debug (Exception.))
   (log :trace "arg1")
 
+  (log (or nil :info) "Booya")
+
   (set-config! [:ns-blacklist] [])
   (set-config! [:ns-blacklist] ["taoensso.timbre*"])
 
diff --git a/src/taoensso/timbre/profiling.clj b/src/taoensso/timbre/profiling.clj
index 041f24d..24c21aa 100644
--- a/src/taoensso/timbre/profiling.clj
+++ b/src/taoensso/timbre/profiling.clj
@@ -110,7 +110,6 @@
   for db appenders to check for this special key and to log profiling stats to
   db in a queryable manner."
   [level name & body]
-  (timbre/assert-valid-level level)
   `(if (timbre/logging-enabled? ~level)
      (profile*
       (fn [name# stats#]