diff --git a/Antlr4.Runtime/Atn/ATNConfigSet.cs b/Antlr4.Runtime/Atn/ATNConfigSet.cs
index 5a2140a48..9dd84b6fd 100644
--- a/Antlr4.Runtime/Atn/ATNConfigSet.cs
+++ b/Antlr4.Runtime/Atn/ATNConfigSet.cs
@@ -33,11 +33,13 @@ using System.Text;
 using Antlr4.Runtime.Atn;
 using Antlr4.Runtime.Misc;
 using Sharpen;
+using IEnumerable = System.Collections.IEnumerable;
+using IEnumerator = System.Collections.IEnumerator;
 
 namespace Antlr4.Runtime.Atn
 {
     /// <author>Sam Harwell</author>
-    public class ATNConfigSet : ISet<ATNConfig>
+    public class ATNConfigSet : IEnumerable<ATNConfig>
     {
         /// <summary>
         /// This maps (state, alt) -&gt; merged
@@ -301,7 +303,12 @@ namespace Antlr4.Runtime.Atn
 
         public virtual IEnumerator<ATNConfig> GetEnumerator()
         {
-            return new ATNConfigSet.ATNConfigSetIterator(this);
+            return configs.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
         }
 
         public virtual object[] ToArray()
@@ -446,13 +453,12 @@ namespace Antlr4.Runtime.Atn
             return true;
         }
 
-        public virtual bool AddAll<_T0>(ICollection<_T0> c) where _T0:ATNConfig
+        public virtual bool AddAll(IEnumerable<ATNConfig> c)
         {
             return AddAll(c, null);
         }
 
-        public virtual bool AddAll<_T0>(ICollection<_T0> c, PredictionContextCache contextCache
-            ) where _T0:ATNConfig
+        public virtual bool AddAll(IEnumerable<ATNConfig> c, PredictionContextCache contextCache)
         {
             EnsureWritable();
             bool changed = false;
diff --git a/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs b/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs
index 6db6c0542..02b061853 100644
--- a/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs
@@ -114,5 +114,15 @@ namespace Antlr4.Runtime.Dfa
         public abstract int Size();
 
         public abstract IDictionary<int, T> ToMap();
+
+        public virtual IEnumerator<KeyValuePair<int, T>> GetEnumerator()
+        {
+            return ToMap().GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
     }
 }
diff --git a/Antlr4.Runtime/Dfa/DFASerializer.cs b/Antlr4.Runtime/Dfa/DFASerializer.cs
index d982e0851..bbf03ef8f 100644
--- a/Antlr4.Runtime/Dfa/DFASerializer.cs
+++ b/Antlr4.Runtime/Dfa/DFASerializer.cs
@@ -85,8 +85,8 @@ namespace Antlr4.Runtime.Dfa
                 states.Sort(new _IComparer_85());
                 foreach (DFAState s in states)
                 {
-                    IDictionary<int, DFAState> edges = s.EdgeMap;
-                    IDictionary<int, DFAState> contextEdges = s.ContextEdgeMap;
+                    IEnumerable<KeyValuePair<int, DFAState>> edges = s.EdgeMap;
+                    IEnumerable<KeyValuePair<int, DFAState>> contextEdges = s.ContextEdgeMap;
                     foreach (KeyValuePair<int, DFAState> entry in edges)
                     {
                         if ((entry.Value == null || entry.Value == ATNSimulator.Error) && !s.IsContextSymbol
diff --git a/Antlr4.Runtime/Dfa/IEdgeMap`1.cs b/Antlr4.Runtime/Dfa/IEdgeMap`1.cs
index 52f79e464..141cb896a 100644
--- a/Antlr4.Runtime/Dfa/IEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/IEdgeMap`1.cs
@@ -35,7 +35,7 @@ using Sharpen;
 namespace Antlr4.Runtime.Dfa
 {
     /// <author>Sam Harwell</author>
-    public interface IEdgeMap<T>
+    public interface IEdgeMap<T> : IEnumerable<KeyValuePair<int, T>>
     {
         int Size();