diff --git a/build-tools/build.xml b/build-tools/build.xml
index 084595c1512..e89f0c7aaac 100644
--- a/build-tools/build.xml
+++ b/build-tools/build.xml
@@ -4,7 +4,7 @@
     <property name="kotlin-home"      location="${output}/ant-test/kotlin-home"/>
     <property name="tests-jar"        location="${tests-dir}/out.jar"/>
     <property name="bootstrap-dir"    location="${basedir}/bootstrap.compiler"/>
-    <property name="failonerror"      value="false"/> <!-- Whether invoking compiled classes should file on error -->
+    <property name="failonerror"      value="true"/> <!-- Whether invoking compiled classes should file on error -->
 
 
     <taskdef resource="net/sf/antcontrib/antlib.xml">
diff --git a/build-tools/test/longer-examples/Life.kt b/build-tools/test/longer-examples/Life.kt
index 7a15da126fd..0c043a44659 100644
--- a/build-tools/test/longer-examples/Life.kt
+++ b/build-tools/test/longer-examples/Life.kt
@@ -153,6 +153,7 @@ fun <K, V> Map<K, V>.set(k : K, v : V) { put(k, v) }
 
 fun comparator<T> (f : (T, T) -> Int) : Comparator<T> = object : Comparator<T> {
     override fun compare(o1 : T, o2 : T) : Int = f(o1, o2)
+    override fun equals(p : Any?) : Boolean = false
 }
 
 val <T> Array<T>.isEmpty : Boolean get() = size == 0
diff --git a/build-tools/test/longer-examples/Maze.kt b/build-tools/test/longer-examples/Maze.kt
index 824ff9cc68c..0e7b6f2bd65 100644
--- a/build-tools/test/longer-examples/Maze.kt
+++ b/build-tools/test/longer-examples/Maze.kt
@@ -214,6 +214,7 @@ fun <K, V> Map<K, V>.set(k : K, v : V) { put(k, v) }
 
 fun comparator<T> (f : (T, T) -> Int) : Comparator<T> = object : Comparator<T> {
     override fun compare(o1 : T, o2 : T) : Int = f(o1, o2)
+    override fun equals(p : Any?) : Boolean = false
 }
 
 fun <T, C: Collection<T>> Array<T>.to(result: C) : C {