diff --git a/src/CsvHelper/Configuration/ClassMap`1.cs b/src/CsvHelper/Configuration/ClassMap`1.cs
index 97b3cabc9..aa5d65d6c 100644
--- a/src/CsvHelper/Configuration/ClassMap`1.cs
+++ b/src/CsvHelper/Configuration/ClassMap`1.cs
@@ -27,7 +27,7 @@ public ClassMap() : base(typeof(TClass)) { }
 	/// <returns>The member mapping.</returns>
 	public virtual MemberMap<TClass, TMember> Map<TMember>(Expression<Func<TClass, TMember?>> expression, bool useExistingMap = true)
 	{
-		var (classMap, member) = GetMemberMap(expression);
+		var classMap = GetMemberMap(expression, out var member);
 		var memberMap = classMap.Map(typeof(TClass), member, useExistingMap); ;
 
 		return (MemberMap<TClass, TMember>)memberMap;
@@ -42,7 +42,7 @@ public virtual MemberMap<TClass, TMember> Map<TMember>(Expression<Func<TClass, T
 	/// <returns>The member mapping.</returns>
 	public virtual MemberMap Map<T>(Expression<Func<T, object?>> expression, bool useExistingMap = true)
 	{
-		var (classMap, member) = GetMemberMap(expression);
+		var classMap = GetMemberMap(expression, out var member);
 		var memberMap = classMap.Map(typeof(TClass), member, useExistingMap);
 
 		return memberMap;
@@ -64,7 +64,7 @@ public virtual MemberReferenceMap References<TClassMap>(Expression<Func<TClass,
 		return References(typeof(TClassMap), member, constructorArgs);
 	}
 
-	private (ClassMap, MemberInfo) GetMemberMap<TModel, TProperty>(Expression<Func<TModel, TProperty?>> expression)
+	private ClassMap GetMemberMap<TModel, TProperty>(Expression<Func<TModel, TProperty?>> expression, out MemberInfo member)
 	{
 		var stack = ReflectionHelper.GetMembers(expression);
 		if (stack.Count == 0)
@@ -73,7 +73,6 @@ public virtual MemberReferenceMap References<TClassMap>(Expression<Func<TClass,
 		}
 
 		ClassMap currentClassMap = this;
-		MemberInfo member;
 
 		if (stack.Count > 1)
 		{
@@ -105,6 +104,6 @@ public virtual MemberReferenceMap References<TClassMap>(Expression<Func<TClass,
 		// Add the member map to the last reference map.
 		member = stack.Pop();
 
-		return (currentClassMap, member);
+		return currentClassMap;
 	}
 }
diff --git a/src/CsvHelper/CsvReader.cs b/src/CsvHelper/CsvReader.cs
index 3fa74c2a0..f34a93fc0 100644
--- a/src/CsvHelper/CsvReader.cs
+++ b/src/CsvHelper/CsvReader.cs
@@ -19,7 +19,7 @@ public class CsvReader : IReader
 	private readonly Lazy<RecordManager> recordManager;
 	private readonly bool detectColumnCountChanges;
 	private readonly Dictionary<string, List<int>> namedIndexes = new Dictionary<string, List<int>>();
-	private readonly Dictionary<string, (string, int)> namedIndexCache = new Dictionary<string, (string, int)>();
+	private readonly Dictionary<string, NameIndex> namedIndexCache = new Dictionary<string, NameIndex>();
 	private readonly Dictionary<Type, TypeConverterOptions> typeConverterOptionsCache = new Dictionary<Type, TypeConverterOptions>();
 	private readonly MemberMapData reusableMemberMapData = new MemberMapData(null);
 	private readonly bool hasHeaderRecord;
@@ -1276,8 +1276,7 @@ public virtual int GetFieldIndex(IEnumerable<string> names, int index = 0, bool
 		var nameKey = string.Join("_", names) + index;
 		if (namedIndexCache.TryGetValue(nameKey, out var cache))
 		{
-			(var cachedName, var cachedIndex) = cache;
-			return namedIndexes[cachedName][cachedIndex];
+			return namedIndexes[cache.Name][cache.Index];
 		}
 
 		// Check all possible names for this field.
@@ -1310,7 +1309,7 @@ public virtual int GetFieldIndex(IEnumerable<string> names, int index = 0, bool
 			return -1;
 		}
 
-		namedIndexCache.Add(nameKey, (name, index));
+		namedIndexCache.Add(nameKey, new NameIndex(name, index));
 
 		return namedIndexes[name][index];
 	}
@@ -1435,4 +1434,31 @@ protected virtual void ParseNamedIndexes()
 			}
 		}
 	}
+
+	private readonly struct NameIndex : IEquatable<NameIndex>
+	{
+		public string Name { get; }
+		public int Index { get; }
+
+		public NameIndex(string name, int index)
+		{
+			Name = name;
+			Index = index;
+		}
+
+		public override bool Equals(object? obj)
+		{
+			return obj is NameIndex index && Equals(index);
+		}
+
+		public bool Equals(NameIndex other)
+		{
+			return Name == other.Name && Index == other.Index;
+		}
+
+		public override int GetHashCode()
+		{
+			return HashCode.Combine(Name, Index);
+		}
+	}
 }