diff --git a/prime.clj/src/prime/clj.clj b/prime.clj/src/prime/clj.clj
index 3d5ee74843ecf3294162057ff1fa281ad940b178..e1ccbc2aab99cc3210968cbc9f2ac3e83d968f73 100644
--- a/prime.clj/src/prime/clj.clj
+++ b/prime.clj/src/prime/clj.clj
@@ -5,10 +5,10 @@
 
 (defn prime? [x]
   (cond
-    (integer? (clojure.math.numeric-tower/sqrt x)) false
+    (integer? (math/sqrt x)) false
     :else (every?
             (fn [y] (not= (mod x y) 0))
-            (range 2 (math/sqrt (math/ceil x))))))
+            (range 2 (math/ceil (math/sqrt x))))))
 
 
 (defn -main