diff --git a/src/library/scala/collection/mutable/HashMap.scala b/src/library/scala/collection/mutable/HashMap.scala
index 6fca75f..91dff4a 100644
--- a/src/library/scala/collection/mutable/HashMap.scala
+++ b/src/library/scala/collection/mutable/HashMap.scala
@@ -82,8 +82,10 @@ extends AbstractMap[A, B]
 
   override def remove(key: A): Option[B] = {
     val e = removeEntry(key)
-    if (e ne null) Some(e.value)
-    else None
+    if (e ne null) {
+      e.next = null               // remove link into hashmap to help tracing gcs
+      Some(e.value)
+    } else None
   }
 
   def += (kv: (A, B)): this.type = {
@@ -92,7 +94,11 @@ extends AbstractMap[A, B]
     this
   }
 
-  def -=(key: A): this.type = { removeEntry(key); this }
+  def -=(key: A): this.type = {
+    val e = removeEntry(key);
+    if (e ne null) e.next = null  // remove link into hashmap to help tracing gcs
+    this
+  }
 
   def iterator = entriesIterator map (e => ((e.key, e.value)))
 
diff --git a/src/library/scala/collection/mutable/LinkedHashMap.scala b/src/library/scala/collection/mutable/LinkedHashMap.scala
index b64504b..5f133d7 100644
--- a/src/library/scala/collection/mutable/LinkedHashMap.scala
+++ b/src/library/scala/collection/mutable/LinkedHashMap.scala
@@ -81,6 +81,11 @@ class LinkedHashMap[A, B] extends AbstractMap[A, B]
       else e.earlier.later = e.later
       if (e.later eq null) lastEntry = e.earlier
       else e.later.earlier = e.earlier
+
+      // remove links into hashmap to help tracing gcs
+      e.earlier = null
+      e.later = null
+
       Some(e.value)
     }
   }
diff --git a/src/library/scala/collection/mutable/LinkedHashSet.scala b/src/library/scala/collection/mutable/LinkedHashSet.scala
index 1768c94..45551ea 100644
--- a/src/library/scala/collection/mutable/LinkedHashSet.scala
+++ b/src/library/scala/collection/mutable/LinkedHashSet.scala
@@ -73,6 +73,11 @@ class LinkedHashSet[A] extends AbstractSet[A]
       else e.earlier.later = e.later
       if (e.later eq null) lastEntry = e.earlier
       else e.later.earlier = e.earlier
+
+      // remove links into hashset to help tracing gcs
+      e.later = null
+      e.earlier = null
+
       true
     }
   }
diff --git a/src/library/scala/collection/parallel/mutable/ParHashMap.scala b/src/library/scala/collection/parallel/mutable/ParHashMap.scala
index bb3737f..f8997fb 100644
--- a/src/library/scala/collection/parallel/mutable/ParHashMap.scala
+++ b/src/library/scala/collection/parallel/mutable/ParHashMap.scala
@@ -77,8 +77,10 @@ self =>
 
   def remove(key: K): Option[V] = {
     val e = removeEntry(key)
-    if (e ne null) Some(e.value)
-    else None
+    if (e ne null) {
+      e.next = null               // remove link into hashmap to help tracing gcs
+      Some(e.value)
+    } else None
   }
 
   def += (kv: (K, V)): this.type = {
@@ -87,7 +89,11 @@ self =>
     this
   }
 
-  def -=(key: K): this.type = { removeEntry(key); this }
+  def -=(key: K): this.type = {
+    val e = removeEntry(key)
+    if (e ne null) e.next = null  // remove link into hashmap to help tracing gcs
+    this
+  }
 
   override def stringPrefix = "ParHashMap"