diff --git a/Antlr4.Runtime/Misc/Utils.cs b/Antlr4.Runtime/Misc/Utils.cs
index 45d6e1ee3..77cdb99ef 100644
--- a/Antlr4.Runtime/Misc/Utils.cs
+++ b/Antlr4.Runtime/Misc/Utils.cs
@@ -27,6 +27,7 @@
  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+using System;
 using System.Collections.Generic;
 using System.Text;
 using Antlr4.Runtime.Misc;
@@ -103,7 +104,7 @@ namespace Antlr4.Runtime.Misc
             return buf.ToString();
         }
 
-        public static void RemoveAll<T, _T1>(IList<T> list, IPredicate<_T1> predicate)
+        public static void RemoveAll<T, _T1>(IList<T> list, Predicate<_T1> predicate)
         {
             int j = 0;
             for (int i = 0; i < list.Count; i++)
@@ -123,23 +124,5 @@ namespace Antlr4.Runtime.Misc
                 list.SubList(j, list.Count).Clear();
             }
         }
-
-        public static void RemoveAll<T, _T1>(IEnumerable<T> iterable, IPredicate<_T1> predicate
-            )
-        {
-            if (iterable is IList<object>)
-            {
-                RemoveAll((IList<T>)iterable, predicate);
-                return;
-            }
-            for (IEnumerator<T> iterator = iterable.GetEnumerator(); iterator.HasNext(); )
-            {
-                T item = iterator.Next();
-                if (predicate.Eval(item))
-                {
-                    iterator.Remove();
-                }
-            }
-        }
     }
 }
diff --git a/reference/antlr4 b/reference/antlr4
index 9209ffea8..55e095830 160000
--- a/reference/antlr4
+++ b/reference/antlr4
@@ -1 +1 @@
-Subproject commit 9209ffea852fc94a198496bdb87babd0def4148e
+Subproject commit 55e0958300f33236e916623077fd356fc6914b6d
diff --git a/reference/sharpen-all-options.txt b/reference/sharpen-all-options.txt
index d4eec06bf..7bda0aaf0 100644
--- a/reference/sharpen-all-options.txt
+++ b/reference/sharpen-all-options.txt
@@ -193,6 +193,9 @@
 -methodMapping org.antlr.v4.runtime.misc.EqualityComparator.hashCode GetHashCode
 -typeMapping org.antlr.v4.runtime.misc.AbstractEqualityComparator<> System.Collections.Generic.EqualityComparer
 -typeMapping org.antlr.v4.runtime.misc.FlexibleHashMap<,> System.Collections.Generic.Dictionary
+-typeMapping org.antlr.v4.runtime.misc.Predicate<> System.Predicate
+-typeMapping org.antlr.v4.runtime.misc.Func0<> System.Func
+-typeMapping org.antlr.v4.runtime.misc.Func1<,> System.Func
 
 -typeMapping org.antlr.v4.runtime.misc.Tuple System.Tuple
 -typeMapping org.antlr.v4.runtime.misc.Tuple2<,> System.Tuple