diff --git a/libraries/kotlin.test/jvm/src/main/kotlin/CollectionAssertions.kt b/libraries/kotlin.test/jvm/src/main/kotlin/CollectionAssertions.kt
index 60a690596f5..26136ba3a35 100644
--- a/libraries/kotlin.test/jvm/src/main/kotlin/CollectionAssertions.kt
+++ b/libraries/kotlin.test/jvm/src/main/kotlin/CollectionAssertions.kt
@@ -3,49 +3,49 @@
  * that can be found in the license/LICENSE.txt file.
  */
 
-@file:Suppress("DEPRECATION")
+@file:Suppress("DEPRECATION_ERROR")
 package kotlin.test
 
 import java.util.*
 
-// TODO: Drop in 1.2
+// TODO: Drop entirely in 1.4
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 class CollectionAssertionSession<E, C: Iterable<E>>(val collection: C)
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 inline fun <E, C: Iterable<E>> assert(collection: C, block: CollectionAssertionSession<E, C>.() -> Unit) {
     CollectionAssertionSession(collection).block()
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <C: Collection<*>> CollectionAssertionSession<*, C>.sizeShouldBe(expectedSize: Int, message: String? = null) {
     assertEquals(expectedSize, collection.size, message ?: "collection should have size $expectedSize but it is ${collection.size}")
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T> CollectionAssertionSession<T, *>.elementAtShouldBe(position: Int, expected: T, message: String? = null) {
     assertEquals(expected, collection.elementAt(position), message ?: "element at $position should be $expected")
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T, C: Iterable<T>> CollectionAssertionSession<T, C>.elementAtShouldComply(position: Int, message: String? = null, predicate: (T) -> Boolean) {
     assertTrue(message) { predicate(collection.elementAt(position)) }
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T> CollectionAssertionSession<T, *>.lastElementShouldBe(expected: T, message: String? = null) {
     assertEquals(expected, collection.last(), message ?: "the last element should be $expected")
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T> CollectionAssertionSession<T, *>.containsAll(vararg elements: T) {
     for (e in elements) {
         assertTrue(message = "Element $e is missing in the collection") { e in collection }
     }
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T, C: Iterable<T>> CollectionAssertionSession<T, C>.shouldBe(expectedElements: Iterable<T>, message: String? = null) {
     val actual = collection.iterator()
     val expected = expectedElements.iterator()
@@ -62,7 +62,7 @@ fun <T, C: Iterable<T>> CollectionAssertionSession<T, C>.shouldBe(expectedElemen
     }
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T, C: Set<T>> CollectionAssertionSession<T, C>.shouldBeSet(other: Set<T>, message: String? = null) {
     for (e in other) {
         if (e !in collection) {
@@ -76,7 +76,7 @@ fun <T, C: Set<T>> CollectionAssertionSession<T, C>.shouldBeSet(other: Set<T>, m
     }
 }
 
-@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.")
+@Deprecated("This is an experimental part of the API. It may be changed or removed in newer releases.", level = DeprecationLevel.ERROR)
 fun <T, C: Set<T>> CollectionAssertionSession<T, C>.shouldBeSet(vararg other: T) {
     val otherSet = HashSet<T>()
     for (e in other) {
diff --git a/libraries/kotlin.test/jvm/src/test/kotlin/CollectionAssertionTest.kt b/libraries/kotlin.test/jvm/src/test/kotlin/CollectionAssertionTest.kt
index e9a24a43bcf..4385dc21458 100644
--- a/libraries/kotlin.test/jvm/src/test/kotlin/CollectionAssertionTest.kt
+++ b/libraries/kotlin.test/jvm/src/test/kotlin/CollectionAssertionTest.kt
@@ -3,7 +3,7 @@
  * that can be found in the license/LICENSE.txt file.
  */
 
-@file:Suppress("DEPRECATION")
+@file:Suppress("DEPRECATION_ERROR")
 
 package kotlin.test.tests