diff --git a/libraries/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/KDocConfig.kt b/libraries/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/KDocConfig.kt
index be27a10e646..8940de717b6 100644
--- a/libraries/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/KDocConfig.kt
+++ b/libraries/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/KDocConfig.kt
@@ -95,7 +95,7 @@ class KDocConfig() {
 
 protected class LongestFirstStringComparator() : Comparator<String> {
     override fun compare(s1: String?, s2: String?): Int {
-        return compareBy(s1, s2, { (s: String) -> s.length() })
+        return compareBy(s1, s2, { (s: String) -> s.length() }, { (s: String) -> s })
     }
 
     override fun equals(obj : Any?) : Boolean {
diff --git a/libraries/stdlib/src/Ordering.kt b/libraries/stdlib/src/Ordering.kt
index 5bb5ca62603..137e8e6d581 100644
--- a/libraries/stdlib/src/Ordering.kt
+++ b/libraries/stdlib/src/Ordering.kt
@@ -1,14 +1,13 @@
 package kotlin
 
-import java.lang.Iterable
-import java.util.Comparator
 import java.util.Comparator
 
 /**
- * Helper method for implementing [[Comparable<T>]] methods using a list of functions
- * to calculate the values to compare
- */
-inline fun <T> compareBy(a: T?, b: T?, vararg functions: Function1<T,Any?>): Int {
+* Helper method for implementing [[Comparable<T>]] methods using a list of functions
+* to calculate the values to compare
+*/
+inline fun <T> compareBy(a: T?, b: T?, vararg functions: Function1<T, Any?>): Int {
+    require(functions.size > 0)
     if (a === b) return 0
     if (a == null) return - 1
     if (b == null) return 1
@@ -18,7 +17,7 @@ inline fun <T> compareBy(a: T?, b: T?, vararg functions: Function1<T,Any?>): Int
         val diff = compareValues(v1, v2)
         if (diff != null) return diff
     }
-    return compareValues(a, b)
+    return 0
 }
 
 /**