diff --git a/src/main/scala/lc/captchas/FilterChallenge.scala b/src/main/scala/lc/captchas/FilterChallenge.scala
index a4508b6..4fcc89d 100644
--- a/src/main/scala/lc/captchas/FilterChallenge.scala
+++ b/src/main/scala/lc/captchas/FilterChallenge.scala
@@ -32,7 +32,7 @@ class FilterChallenge extends ChallengeProvider {
     val r = new scala.util.Random
     val alphabet = "abcdefghijklmnopqrstuvwxyz"
     val n = 8
-    val secret = Stream.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
+    val secret = LazyList.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
     val canvas = new BufferedImage(225, 50, BufferedImage.TYPE_INT_RGB)
     val g = canvas.createGraphics()
     g.setColor(Color.WHITE)
diff --git a/src/main/scala/lc/captchas/RainDropsCaptcha.scala b/src/main/scala/lc/captchas/RainDropsCaptcha.scala
index 2788096..0b08dcd 100644
--- a/src/main/scala/lc/captchas/RainDropsCaptcha.scala
+++ b/src/main/scala/lc/captchas/RainDropsCaptcha.scala
@@ -58,7 +58,7 @@ class RainDropsCP extends ChallengeProvider {
 
   def returnChallenge(): Challenge = {
     val r = new scala.util.Random
-    val secret = Stream.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
+    val secret = LazyList.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
     val width = 450
     val height = 100
     val imgType = BufferedImage.TYPE_INT_RGB