diff --git a/src/NHibernate.Test/Async/NHSpecificTest/GH1180/FixtureByCode.cs b/src/NHibernate.Test/Async/NHSpecificTest/GH1180/FixtureByCode.cs
new file mode 100644
index 00000000000..baf5bbacdbb
--- /dev/null
+++ b/src/NHibernate.Test/Async/NHSpecificTest/GH1180/FixtureByCode.cs
@@ -0,0 +1,146 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by AsyncGenerator.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+
+using NHibernate.Cfg.MappingSchema;
+using NHibernate.Criterion;
+using NHibernate.Mapping.ByCode;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.GH1180
+{
+	using System.Threading.Tasks;
+	[KnownBug("NH-3847 (GH-1180)")]
+	[TestFixture]
+	public class ByCodeFixtureAsync : TestCaseMappingByCode
+	{
+		protected override HbmMapping GetMappings()
+		{
+			var mapper = new ModelMapper();
+
+			mapper.Class<Entity>(rc =>
+			{
+				rc.Id(x => x.Id, m => m.Generator(Generators.GuidComb));
+				rc.Property(x => x.Name, m => { m.Length(10); });
+				rc.Property(x => x.Amount, m => { m.Precision(8); m.Scale(2); });
+			});
+
+			return mapper.CompileMappingForAllExplicitlyAddedEntities();
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.CreateQuery("delete from System.Object").ExecuteUpdate();
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public async Task StringTypesAsync()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				// data
+				await (session.SaveAsync(new Entity {Name = "Alpha"}));
+				await (session.SaveAsync(new Entity {Name = "Beta"}));
+				await (session.SaveAsync(new Entity {Name = "Gamma"}));
+
+				await (transaction.CommitAsync());
+			}
+
+			// whenTrue is constant, whenFalse is property -> works even before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Not(
+						Restrictions.Like(nameof(Entity.Name), "B%")),
+					Projections.Constant("other"),
+					Projections.Property(nameof(Entity.Name)));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = await (tagCriteria.ListAsync());
+
+				Assert.That(results, Is.EquivalentTo(new[] {"other", "Beta", "other"}));
+			}
+
+			// whenTrue is property, whenFalse is constant -> fails before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Like(nameof(Entity.Name), "B%"),
+					Projections.Property(nameof(Entity.Name)),
+					Projections.Constant("other"));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = await (tagCriteria.ListAsync());
+
+				Assert.That(results, Is.EquivalentTo(new[] {"other", "Beta", "other"}));
+			}
+		}
+
+		[Test]
+		public async Task DecimalTypesAsync()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				await (session.SaveAsync(new Entity {Amount = 3.14m}));
+				await (session.SaveAsync(new Entity {Amount = 42.13m}));
+				await (session.SaveAsync(new Entity {Amount = 17.99m}));
+
+				await (transaction.CommitAsync());
+			}
+
+			// whenTrue is constant, whenFalse is property -> works even before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Not(
+						Restrictions.Ge(nameof(Entity.Amount), 20m)),
+					Projections.Constant(20m),
+					Projections.Property(nameof(Entity.Amount)));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = await (tagCriteria.ListAsync());
+
+				Assert.That(results, Is.EquivalentTo(new[] {20m, 42.13m, 20m}));
+			}
+
+			// whenTrue is property, whenFalse is constant -> fails before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Ge(nameof(Entity.Amount), 20m),
+					Projections.Property(nameof(Entity.Amount)),
+					Projections.Constant(20m));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = await (tagCriteria.ListAsync());
+
+				Assert.That(results, Is.EquivalentTo(new[] {20m, 42.13m, 20m}));
+			}
+		}
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/GH1180/Entity.cs b/src/NHibernate.Test/NHSpecificTest/GH1180/Entity.cs
new file mode 100644
index 00000000000..bf16619beb8
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/GH1180/Entity.cs
@@ -0,0 +1,11 @@
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.GH1180
+{
+	internal class Entity
+	{
+		public virtual Guid Id { get; set; }
+		public virtual string Name { get; set; }
+		public virtual decimal Amount { get; set; }
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/GH1180/FixtureByCode.cs b/src/NHibernate.Test/NHSpecificTest/GH1180/FixtureByCode.cs
new file mode 100644
index 00000000000..a7590840459
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/GH1180/FixtureByCode.cs
@@ -0,0 +1,135 @@
+using NHibernate.Cfg.MappingSchema;
+using NHibernate.Criterion;
+using NHibernate.Mapping.ByCode;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.GH1180
+{
+	[KnownBug("NH-3847 (GH-1180)")]
+	[TestFixture]
+	public class ByCodeFixture : TestCaseMappingByCode
+	{
+		protected override HbmMapping GetMappings()
+		{
+			var mapper = new ModelMapper();
+
+			mapper.Class<Entity>(rc =>
+			{
+				rc.Id(x => x.Id, m => m.Generator(Generators.GuidComb));
+				rc.Property(x => x.Name, m => { m.Length(10); });
+				rc.Property(x => x.Amount, m => { m.Precision(8); m.Scale(2); });
+			});
+
+			return mapper.CompileMappingForAllExplicitlyAddedEntities();
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.CreateQuery("delete from System.Object").ExecuteUpdate();
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public void StringTypes()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				// data
+				session.Save(new Entity {Name = "Alpha"});
+				session.Save(new Entity {Name = "Beta"});
+				session.Save(new Entity {Name = "Gamma"});
+
+				transaction.Commit();
+			}
+
+			// whenTrue is constant, whenFalse is property -> works even before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Not(
+						Restrictions.Like(nameof(Entity.Name), "B%")),
+					Projections.Constant("other"),
+					Projections.Property(nameof(Entity.Name)));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = tagCriteria.List();
+
+				Assert.That(results, Is.EquivalentTo(new[] {"other", "Beta", "other"}));
+			}
+
+			// whenTrue is property, whenFalse is constant -> fails before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Like(nameof(Entity.Name), "B%"),
+					Projections.Property(nameof(Entity.Name)),
+					Projections.Constant("other"));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = tagCriteria.List();
+
+				Assert.That(results, Is.EquivalentTo(new[] {"other", "Beta", "other"}));
+			}
+		}
+
+		[Test]
+		public void DecimalTypes()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.Save(new Entity {Amount = 3.14m});
+				session.Save(new Entity {Amount = 42.13m});
+				session.Save(new Entity {Amount = 17.99m});
+
+				transaction.Commit();
+			}
+
+			// whenTrue is constant, whenFalse is property -> works even before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Not(
+						Restrictions.Ge(nameof(Entity.Amount), 20m)),
+					Projections.Constant(20m),
+					Projections.Property(nameof(Entity.Amount)));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = tagCriteria.List();
+
+				Assert.That(results, Is.EquivalentTo(new[] {20m, 42.13m, 20m}));
+			}
+
+			// whenTrue is property, whenFalse is constant -> fails before the fix
+			using (var session = OpenSession())
+			{
+				ICriteria tagCriteria = session.CreateCriteria(typeof(Entity));
+
+				var conditionalProjection = Projections.Conditional(
+					Restrictions.Ge(nameof(Entity.Amount), 20m),
+					Projections.Property(nameof(Entity.Amount)),
+					Projections.Constant(20m));
+				tagCriteria.SetProjection(conditionalProjection);
+
+				// run query
+				var results = tagCriteria.List();
+
+				Assert.That(results, Is.EquivalentTo(new[] {20m, 42.13m, 20m}));
+			}
+		}
+	}
+}
diff --git a/src/NHibernate/Type/NullableType.cs b/src/NHibernate/Type/NullableType.cs
index e84b6df48da..883894ee971 100644
--- a/src/NHibernate/Type/NullableType.cs
+++ b/src/NHibernate/Type/NullableType.cs
@@ -377,6 +377,15 @@ public override int GetHashCode()
 			return (SqlType.GetHashCode() / 2) + (Name.GetHashCode() / 2);
 		}
 
+		/// <summary>
+		/// Provides a more descriptive string representation by reporting the properties that are important for equality. 
+		/// Useful in error messages.
+		/// </summary>
+		public override string ToString()
+		{
+			return $"{base.ToString()} (SqlType: {SqlType})";
+		}
+
 		#endregion
 	}
 }