diff --git a/src/NHibernate.Test/CollectionTest/PersistentCollectionsFixture.cs b/src/NHibernate.Test/CollectionTest/PersistentCollectionsFixture.cs
index 5a7f9679773..03439d8a47a 100644
--- a/src/NHibernate.Test/CollectionTest/PersistentCollectionsFixture.cs
+++ b/src/NHibernate.Test/CollectionTest/PersistentCollectionsFixture.cs
@@ -36,5 +36,22 @@ public void AddRangeWorksCorrectly()
 			
 			Assert.That(items, Is.EqualTo(new[] {"A", "B", "C", "D", "E"}));
 		}
+
+		[Test]
+		public void SelectManyWorksCorrectlyWithIReadOnlyCollection()
+		{
+			var bags = new IReadOnlyCollection<string>[]
+			{
+				new List<string> {"A"},
+				new PersistentGenericBag<string>(null, new[] {"B"}),
+				new PersistentIdentifierBag<string>(null, new[] {"C"}),
+				(IReadOnlyList<string>)new PersistentGenericList<string>(null, new[] {"D"}),
+				new PersistentGenericSet<string>(null, new HashSet<string> {"E"})
+			};
+			
+			var items = bags.SelectMany(b => b).ToArray();
+
+			Assert.That(items, Is.EqualTo(new[] {"A", "B", "C", "D", "E"}));
+		}
 	}
 }
diff --git a/src/NHibernate/Async/Collection/Generic/PersistentGenericBag.cs b/src/NHibernate/Async/Collection/Generic/PersistentGenericBag.cs
index ca332f273ec..de777215a65 100644
--- a/src/NHibernate/Async/Collection/Generic/PersistentGenericBag.cs
+++ b/src/NHibernate/Async/Collection/Generic/PersistentGenericBag.cs
@@ -27,7 +27,7 @@ namespace NHibernate.Collection.Generic
 {
 	using System.Threading.Tasks;
 	using System.Threading;
-	public partial class PersistentGenericBag<T> : AbstractPersistentCollection, IList<T>, IList, IQueryable<T>
+	public partial class PersistentGenericBag<T> : AbstractPersistentCollection, IList<T>, IReadOnlyList<T>, IList, IQueryable<T>
 	{
 
 		public override async Task<object> DisassembleAsync(ICollectionPersister persister, CancellationToken cancellationToken)
diff --git a/src/NHibernate/Async/Collection/Generic/PersistentGenericIdentifierBag.cs b/src/NHibernate/Async/Collection/Generic/PersistentGenericIdentifierBag.cs
index 80f8c950ec2..7250c95ad55 100644
--- a/src/NHibernate/Async/Collection/Generic/PersistentGenericIdentifierBag.cs
+++ b/src/NHibernate/Async/Collection/Generic/PersistentGenericIdentifierBag.cs
@@ -28,7 +28,7 @@ namespace NHibernate.Collection.Generic
 {
 	using System.Threading.Tasks;
 	using System.Threading;
-	public partial class PersistentIdentifierBag<T> : AbstractPersistentCollection, IList<T>, IList, IQueryable<T>
+	public partial class PersistentIdentifierBag<T> : AbstractPersistentCollection, IList<T>, IReadOnlyList<T>, IList, IQueryable<T>
 	{
 
 		/// <summary>
diff --git a/src/NHibernate/Async/Collection/Generic/PersistentGenericList.cs b/src/NHibernate/Async/Collection/Generic/PersistentGenericList.cs
index e6bcfa3812a..1a1fe094e62 100644
--- a/src/NHibernate/Async/Collection/Generic/PersistentGenericList.cs
+++ b/src/NHibernate/Async/Collection/Generic/PersistentGenericList.cs
@@ -27,7 +27,7 @@ namespace NHibernate.Collection.Generic
 {
 	using System.Threading.Tasks;
 	using System.Threading;
-	public partial class PersistentGenericList<T> : AbstractPersistentCollection, IList<T>, IList, IQueryable<T>
+	public partial class PersistentGenericList<T> : AbstractPersistentCollection, IList<T>, IReadOnlyList<T>, IList, IQueryable<T>
 	{
 
 		//Since 5.3
diff --git a/src/NHibernate/Async/Collection/Generic/PersistentGenericMap.cs b/src/NHibernate/Async/Collection/Generic/PersistentGenericMap.cs
index 9f8d0090ea4..567046ef15e 100644
--- a/src/NHibernate/Async/Collection/Generic/PersistentGenericMap.cs
+++ b/src/NHibernate/Async/Collection/Generic/PersistentGenericMap.cs
@@ -27,7 +27,7 @@ namespace NHibernate.Collection.Generic
 {
 	using System.Threading.Tasks;
 	using System.Threading;
-	public partial class PersistentGenericMap<TKey, TValue> : AbstractPersistentCollection, IDictionary<TKey, TValue>, ICollection
+	public partial class PersistentGenericMap<TKey, TValue> : AbstractPersistentCollection, IDictionary<TKey, TValue>, IReadOnlyDictionary<TKey, TValue>, ICollection
 	{
 
 		//Since 5.3
diff --git a/src/NHibernate/Async/Collection/Generic/PersistentGenericSet.cs b/src/NHibernate/Async/Collection/Generic/PersistentGenericSet.cs
index 9e5cb020340..d28409ada26 100644
--- a/src/NHibernate/Async/Collection/Generic/PersistentGenericSet.cs
+++ b/src/NHibernate/Async/Collection/Generic/PersistentGenericSet.cs
@@ -28,7 +28,7 @@ namespace NHibernate.Collection.Generic
 {
 	using System.Threading.Tasks;
 	using System.Threading;
-	public partial class PersistentGenericSet<T> : AbstractPersistentCollection, ISet<T>, IQueryable<T>
+	public partial class PersistentGenericSet<T> : AbstractPersistentCollection, ISet<T>, IReadOnlyCollection<T>, IQueryable<T>
 	{
 
 		//Since 5.3
diff --git a/src/NHibernate/Collection/Generic/PersistentGenericBag.cs b/src/NHibernate/Collection/Generic/PersistentGenericBag.cs
index d58be9c9a94..c8bd0e86793 100644
--- a/src/NHibernate/Collection/Generic/PersistentGenericBag.cs
+++ b/src/NHibernate/Collection/Generic/PersistentGenericBag.cs
@@ -25,7 +25,7 @@ namespace NHibernate.Collection.Generic
 	/// <remarks>The underlying collection used is an <see cref="List{T}"/></remarks>
 	[Serializable]
 	[DebuggerTypeProxy(typeof (CollectionProxy<>))]
-	public partial class PersistentGenericBag<T> : AbstractPersistentCollection, IList<T>, IList, IQueryable<T>
+	public partial class PersistentGenericBag<T> : AbstractPersistentCollection, IList<T>, IReadOnlyList<T>, IList, IQueryable<T>
 	{
 		// TODO NH: find a way to writeonce (no duplicated code from PersistentBag)
 
diff --git a/src/NHibernate/Collection/Generic/PersistentGenericIdentifierBag.cs b/src/NHibernate/Collection/Generic/PersistentGenericIdentifierBag.cs
index b7b23ca80a6..884d454b76e 100644
--- a/src/NHibernate/Collection/Generic/PersistentGenericIdentifierBag.cs
+++ b/src/NHibernate/Collection/Generic/PersistentGenericIdentifierBag.cs
@@ -33,7 +33,7 @@ namespace NHibernate.Collection.Generic
 	/// </remarks>
 	[Serializable]
 	[DebuggerTypeProxy(typeof (CollectionProxy<>))]
-	public partial class PersistentIdentifierBag<T> : AbstractPersistentCollection, IList<T>, IList, IQueryable<T>
+	public partial class PersistentIdentifierBag<T> : AbstractPersistentCollection, IList<T>, IReadOnlyList<T>, IList, IQueryable<T>
 	{
 		/* NH considerations:
 		 * For various reason we know that the underlining type will be a List<T> or a 
diff --git a/src/NHibernate/Collection/Generic/PersistentGenericList.cs b/src/NHibernate/Collection/Generic/PersistentGenericList.cs
index 4e54262a85e..bf8082395f1 100644
--- a/src/NHibernate/Collection/Generic/PersistentGenericList.cs
+++ b/src/NHibernate/Collection/Generic/PersistentGenericList.cs
@@ -22,7 +22,7 @@ namespace NHibernate.Collection.Generic
 	/// <remarks>The underlying collection used is a <see cref="List{T}"/></remarks>
 	[Serializable]
 	[DebuggerTypeProxy(typeof (CollectionProxy<>))]
-	public partial class PersistentGenericList<T> : AbstractPersistentCollection, IList<T>, IList, IQueryable<T>
+	public partial class PersistentGenericList<T> : AbstractPersistentCollection, IList<T>, IReadOnlyList<T>, IList, IQueryable<T>
 	{
 		protected IList<T> WrappedList;
 
diff --git a/src/NHibernate/Collection/Generic/PersistentGenericMap.cs b/src/NHibernate/Collection/Generic/PersistentGenericMap.cs
index 20f4d5ba657..6133897c80d 100644
--- a/src/NHibernate/Collection/Generic/PersistentGenericMap.cs
+++ b/src/NHibernate/Collection/Generic/PersistentGenericMap.cs
@@ -23,7 +23,7 @@ namespace NHibernate.Collection.Generic
 	/// <typeparam name="TValue">The type of the elements in the IDictionary.</typeparam>
 	[Serializable]
 	[DebuggerTypeProxy(typeof(DictionaryProxy<,>))]
-	public partial class PersistentGenericMap<TKey, TValue> : AbstractPersistentCollection, IDictionary<TKey, TValue>, ICollection
+	public partial class PersistentGenericMap<TKey, TValue> : AbstractPersistentCollection, IDictionary<TKey, TValue>, IReadOnlyDictionary<TKey, TValue>, ICollection
 	{
 		protected IDictionary<TKey, TValue> WrappedMap;
 		private readonly ICollection<TValue> _wrappedValues;
@@ -360,6 +360,16 @@ public ICollection<TValue> Values
 			}
 		}
 
+		IEnumerable<TKey> IReadOnlyDictionary<TKey, TValue>.Keys
+		{
+			get { return Keys; }
+		}
+
+		IEnumerable<TValue> IReadOnlyDictionary<TKey, TValue>.Values
+		{
+			get { return Values; }
+		}
+
 		#endregion
 
 		#region ICollection<KeyValuePair<TKey,TValue>> Members
diff --git a/src/NHibernate/Collection/Generic/PersistentGenericSet.cs b/src/NHibernate/Collection/Generic/PersistentGenericSet.cs
index 16a6169ce0c..03a273cd32e 100644
--- a/src/NHibernate/Collection/Generic/PersistentGenericSet.cs
+++ b/src/NHibernate/Collection/Generic/PersistentGenericSet.cs
@@ -21,7 +21,7 @@ namespace NHibernate.Collection.Generic
 	/// </summary>
 	[Serializable]
 	[DebuggerTypeProxy(typeof(CollectionProxy<>))]
-	public partial class PersistentGenericSet<T> : AbstractPersistentCollection, ISet<T>, IQueryable<T>
+	public partial class PersistentGenericSet<T> : AbstractPersistentCollection, ISet<T>, IReadOnlyCollection<T>, IQueryable<T>
 	{
 		/// <summary>
 		/// The <see cref="ISet{T}"/> that NHibernate is wrapping.
diff --git a/src/NHibernate/Collection/Generic/SetHelpers/ISetSnapshot.cs b/src/NHibernate/Collection/Generic/SetHelpers/ISetSnapshot.cs
index 3b86f42f41a..20f9983911f 100644
--- a/src/NHibernate/Collection/Generic/SetHelpers/ISetSnapshot.cs
+++ b/src/NHibernate/Collection/Generic/SetHelpers/ISetSnapshot.cs
@@ -3,8 +3,8 @@
 
 namespace NHibernate.Collection.Generic.SetHelpers
 {
-	internal interface ISetSnapshot<T> : ICollection<T>, ICollection
+	internal interface ISetSnapshot<T> : ICollection<T>, IReadOnlyCollection<T>, ICollection
 	{
 		bool TryGetValue(T element, out T value);
 	}
-}
\ No newline at end of file
+}
diff --git a/src/NHibernate/Collection/Generic/SetHelpers/SetSnapShot.cs b/src/NHibernate/Collection/Generic/SetHelpers/SetSnapShot.cs
index 70492c45532..143d7f2564d 100644
--- a/src/NHibernate/Collection/Generic/SetHelpers/SetSnapShot.cs
+++ b/src/NHibernate/Collection/Generic/SetHelpers/SetSnapShot.cs
@@ -83,6 +83,11 @@ int ICollection<T>.Count
 			get { return _elements.Count; }
 		}
 
+		int IReadOnlyCollection<T>.Count
+		{
+			get { return _elements.Count; }
+		}
+
 		public bool IsReadOnly
 		{
 			get { return ((ICollection<T>)_elements).IsReadOnly; }
@@ -101,4 +106,4 @@ public bool TryGetValue(T element, out T value)
 			return false;
 		}
 	}
-}
\ No newline at end of file
+}