diff --git a/lib/securerandom.rb b/lib/securerandom.rb
index 6079fdb..f39605d 100644
--- a/lib/securerandom.rb
+++ b/lib/securerandom.rb
@@ -48,6 +48,9 @@ class << self
     #
     # See Random.bytes
     def bytes(n)
+      unless Integer === n
+        n = Integer.try_convert(n) or raise TypeError, "size must be an integer"
+      end
       return gen_random(n)
     end