diff --git a/core/builtins/src/kotlin/internal/progressionUtil.kt b/core/builtins/src/kotlin/internal/progressionUtil.kt
index 75166592522..e6d158be49e 100644
--- a/core/builtins/src/kotlin/internal/progressionUtil.kt
+++ b/core/builtins/src/kotlin/internal/progressionUtil.kt
@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package kotlin.internal
@@ -41,8 +30,11 @@ private fun differenceModulo(a: Long, b: Long, c: Long): Long {
  * from [start] to [end] in case of a positive [step], or from [end] to [start] in case of a negative
  * [step].
  *
- * No validation on passed parameters is performed. The given parameters should satisfy the condition: either
- * `step > 0` and `start >= end`, or `step < 0` and`start >= end`.
+ * No validation on passed parameters is performed. The given parameters should satisfy the condition:
+ *
+ * - either `step > 0` and `start <= end`,
+ * - or `step < 0` and `start >= end`.
+ *
  * @param start first element of the progression
  * @param end ending bound for the progression
  * @param step increment, or difference of successive elements in the progression
@@ -67,8 +59,11 @@ internal fun getProgressionLastElement(start: Int, end: Int, step: Int): Int {
  * from [start] to [end] in case of a positive [step], or from [end] to [start] in case of a negative
  * [step].
  *
- * No validation on passed parameters is performed. The given parameters should satisfy the condition: either
- * `step > 0` and `start >= end`, or `step < 0` and`start >= end`.
+ * No validation on passed parameters is performed. The given parameters should satisfy the condition:
+ *
+ * - either `step > 0` and `start <= end`,
+ * - or `step < 0` and `start >= end`.
+ *
  * @param start first element of the progression
  * @param end ending bound for the progression
  * @param step increment, or difference of successive elements in the progression