diff --git a/testcases/BubbleSort.scala b/testcases/BubbleSort.scala
index 5249f4fbe33f31ef8b963d3652b7e26747347629..8e85143ac10414572114f6a24c09e194853af8de 100644
--- a/testcases/BubbleSort.scala
+++ b/testcases/BubbleSort.scala
@@ -5,7 +5,7 @@ import leon.Utils._
 object BubbleSort {
 
   def sort(a: Array[Int]): Array[Int] = ({
-    require(a.length >= 0)
+    require(a.length >= 1)
     var i = a.length - 1
     var j = 0
     val sa = a