diff --git a/isprime.l b/isprime.l
index f938b6f..77f9239 100644
--- a/isprime.l
+++ b/isprime.l
@@ -22,17 +22,19 @@
 # Probabilistic prime check
 (de prime? (N X)
    (default X 32)
-   (and
-      (> N 1)
-      (bit? 1 N)
-      (let (Q (dec N)  K 0)
-         (until (bit? 1 Q)
-            (setq
-               Q  (>> 1 Q)
-               K  (inc K) ) )
-         (do X
-            (NIL (_prim? N Q K))
-            T ) ) ) )
+   (or
+      (== N 2)
+      (and
+         (> N 1)
+         (bit? 1 N)
+         (let (Q (dec N)  K 0)
+            (until (bit? 1 Q)
+               (setq
+                  Q  (>> 1 Q)
+                  K  (inc K) ) )
+            (do X
+               (NIL (_prim? N Q K))
+               T ) ) ) ) )
 
 # (Knuth Vol.2, p.379)
 (de _prim? (N Q K)
diff --git a/test-wycheproof.l b/test-wycheproof.l
index 6854aae..d912219 100644
--- a/test-wycheproof.l
+++ b/test-wycheproof.l
@@ -5,7 +5,7 @@
       (let
          (N (hex (cdr (assoc "value" L)))
             R (cdr (assoc "result" L))
-            I (prime? N 64) )
+            I (prime? N) )
          (prin ".")
          (flush)
          (cond