diff --git a/src/DotNet.MultiMap/MultiMapHashSet.cs b/src/DotNet.MultiMap/MultiMapHashSet.cs
index 0d26010..8b96bd7 100644
--- a/src/DotNet.MultiMap/MultiMapHashSet.cs
+++ b/src/DotNet.MultiMap/MultiMapHashSet.cs
@@ -96,14 +96,13 @@ public MultiMapHashSet(IEnumerable<KeyValuePair<TKey, HashSet<TValue>>> collecti
         /// <returns>true if the value has  been map to the specified key element; otherwise, false.</returns>
         public bool TryToAddMapping(TKey key, TValue val)
         {
-            if (ContainsKey(key))
+            if (TryGetValue(key, out var set))
             {
-                var set = this[key];
                 return set.Add(val);
             }
-            var tmp = new HashSet<TValue>();
+            var tmp = new HashSet<TValue> { val };
             Add(key, tmp);
-            return tmp.Add(val);
+            return true;
         }
 
         /// <summary>
@@ -115,9 +114,8 @@ public bool TryToAddMapping(TKey key, TValue val)
         public bool TryToRemoveMapping(TKey key, TValue val)
         {
             bool result = false;
-            if (ContainsKey(key))
+            if (TryGetValue(key, out var set))
             {
-                var set = this[key];
                 result = set.Remove(val);
                 if (set.Count == 0)
                 {
@@ -135,13 +133,8 @@ public bool TryToRemoveMapping(TKey key, TValue val)
         /// <returns>the number of links (duplicates).</returns>
         public int ContainsMapping(TKey key, TValue val)
         {
-            if (ContainsKey(key))
-            {
-                var set = this[key];
-                if (set.Contains(val))
-                {
-                    return 1;
-                }
+            if (TryGetValue(key, out var set) && set.Contains(val)) {
+                return 1;
             }
             return 0;
         }
diff --git a/src/DotNet.MultiMap/MultiMapList.cs b/src/DotNet.MultiMap/MultiMapList.cs
index b643f5e..9af8856 100644
--- a/src/DotNet.MultiMap/MultiMapList.cs
+++ b/src/DotNet.MultiMap/MultiMapList.cs
@@ -99,16 +99,14 @@ public MultiMapList(IEnumerable<KeyValuePair<TKey, List<TValue>>> collection, IE
         /// <returns>true if the value has  been map to the specified key element; otherwise, false.</returns>
         public bool TryToAddMapping(TKey key, TValue val)
         {
-            if (ContainsKey(key))
+            if (TryGetValue(key, out var set))
             {
-                var set = this[key];
                 set.Add(val);
             }
             else
             {
-                var tmp = new List<TValue>();
+                var tmp = new List<TValue> { val };
                 Add(key, tmp);
-                tmp.Add(val);
             }
             return true;
         }
@@ -122,12 +120,10 @@ public bool TryToAddMapping(TKey key, TValue val)
         public bool TryToRemoveMapping(TKey key, TValue val)
         {
             bool result = false;
-            if (ContainsKey(key))
+            if (TryGetValue(key, out var set))
             {
-                var set = this[key];
                 result = set.Remove(val);
-                if (set.Count == 0)
-                {
+                if (set.Count == 0) {
                     Remove(key);
                 }
             }
@@ -142,9 +138,8 @@ public bool TryToRemoveMapping(TKey key, TValue val)
         /// <returns>the number of links (duplicates).</returns>
         public int ContainsMapping(TKey key, TValue val)
         {
-            if (ContainsKey(key))
+            if (TryGetValue(key, out var set))
             {
-                var set = this[key];
                 return set.Count((v) => v.Equals(val));
             }
             return 0;