diff --git a/src/NHibernate.Test/Async/Criteria/Lambda/FunctionsIntegrationFixture.cs b/src/NHibernate.Test/Async/Criteria/Lambda/FunctionsIntegrationFixture.cs
index e21a2e3f6b2..91296d9f638 100644
--- a/src/NHibernate.Test/Async/Criteria/Lambda/FunctionsIntegrationFixture.cs
+++ b/src/NHibernate.Test/Async/Criteria/Lambda/FunctionsIntegrationFixture.cs
@@ -145,9 +145,6 @@ public async Task FunctionsToLowerToUpperAsync()
 		[Test]
 		public async Task ConcatAsync()
 		{
-			if (TestDialect.HasBrokenTypeInferenceOnSelectedParameters)
-				Assert.Ignore("Current dialect does not support this test");
-
 			using (var s = OpenSession())
 			using (s.BeginTransaction())
 			{
diff --git a/src/NHibernate.Test/Async/Criteria/ProjectionsTest.cs b/src/NHibernate.Test/Async/Criteria/ProjectionsTest.cs
index aca0e5d3660..28fd672ccab 100644
--- a/src/NHibernate.Test/Async/Criteria/ProjectionsTest.cs
+++ b/src/NHibernate.Test/Async/Criteria/ProjectionsTest.cs
@@ -69,9 +69,6 @@ protected override void OnTearDown()
 		[Test]
 		public async Task UsingSqlFunctions_ConcatAsync()
 		{
-			if (TestDialect.HasBrokenTypeInferenceOnSelectedParameters)
-				Assert.Ignore("Current dialect does not support this test");
-
 			using (ISession session = Sfi.OpenSession())
 			{
 				string result = await (session.CreateCriteria(typeof(Student))
@@ -89,12 +86,8 @@ public async Task UsingSqlFunctions_ConcatAsync()
 		[Test]
 		public async Task UsingSqlFunctions_Concat_WithCastAsync()
 		{
-			if(Dialect is Oracle8iDialect)
-			{
+			if (Dialect is Oracle8iDialect)
 				Assert.Ignore("Not supported by the active dialect:{0}.", Dialect);
-			}
-			if (TestDialect.HasBrokenTypeInferenceOnSelectedParameters)
-				Assert.Ignore("Current dialect does not support this test");
 
 			using (ISession session = Sfi.OpenSession())
 			{
diff --git a/src/NHibernate.Test/Async/Hql/HQLFunctions.cs b/src/NHibernate.Test/Async/Hql/HQLFunctions.cs
index a9c304aaa66..5042515aa99 100644
--- a/src/NHibernate.Test/Async/Hql/HQLFunctions.cs
+++ b/src/NHibernate.Test/Async/Hql/HQLFunctions.cs
@@ -1142,6 +1142,25 @@ public async Task ConcatAsync()
 				}
 			}
 		}
+		
+		[Test]
+		public async Task ConcatWithNullAsync()
+		{
+			AssumeFunctionSupported("concat");
+			using (var s = OpenSession())
+			{
+				var a1 = new Animal("abcdef", 1f);
+				await (s.SaveAsync(a1));
+				await (s.FlushAsync());
+			}
+
+			using (var s = OpenSession())
+			{
+				var hql = "select concat(a.Description,null) from Animal a";
+				var lresult = await (s.CreateQuery(hql).ListAsync<string>());
+				Assert.That(lresult[0], Is.EqualTo("abcdef"));
+			}
+		}
 
 		[Test]
 		public async Task HourMinuteSecondAsync()
diff --git a/src/NHibernate.Test/Criteria/Lambda/FunctionsIntegrationFixture.cs b/src/NHibernate.Test/Criteria/Lambda/FunctionsIntegrationFixture.cs
index 7d5b7d014cf..202487c8f1f 100644
--- a/src/NHibernate.Test/Criteria/Lambda/FunctionsIntegrationFixture.cs
+++ b/src/NHibernate.Test/Criteria/Lambda/FunctionsIntegrationFixture.cs
@@ -134,9 +134,6 @@ public void FunctionsToLowerToUpper()
 		[Test]
 		public void Concat()
 		{
-			if (TestDialect.HasBrokenTypeInferenceOnSelectedParameters)
-				Assert.Ignore("Current dialect does not support this test");
-
 			using (var s = OpenSession())
 			using (s.BeginTransaction())
 			{
diff --git a/src/NHibernate.Test/Criteria/ProjectionsTest.cs b/src/NHibernate.Test/Criteria/ProjectionsTest.cs
index 0eb03b33a60..c53b0158639 100644
--- a/src/NHibernate.Test/Criteria/ProjectionsTest.cs
+++ b/src/NHibernate.Test/Criteria/ProjectionsTest.cs
@@ -58,9 +58,6 @@ protected override void OnTearDown()
 		[Test]
 		public void UsingSqlFunctions_Concat()
 		{
-			if (TestDialect.HasBrokenTypeInferenceOnSelectedParameters)
-				Assert.Ignore("Current dialect does not support this test");
-
 			using (ISession session = Sfi.OpenSession())
 			{
 				string result = session.CreateCriteria(typeof(Student))
@@ -78,12 +75,8 @@ public void UsingSqlFunctions_Concat()
 		[Test]
 		public void UsingSqlFunctions_Concat_WithCast()
 		{
-			if(Dialect is Oracle8iDialect)
-			{
+			if (Dialect is Oracle8iDialect)
 				Assert.Ignore("Not supported by the active dialect:{0}.", Dialect);
-			}
-			if (TestDialect.HasBrokenTypeInferenceOnSelectedParameters)
-				Assert.Ignore("Current dialect does not support this test");
 
 			using (ISession session = Sfi.OpenSession())
 			{
diff --git a/src/NHibernate.Test/Hql/HQLFunctions.cs b/src/NHibernate.Test/Hql/HQLFunctions.cs
index 1a2b80b0efd..0a23dc1e675 100644
--- a/src/NHibernate.Test/Hql/HQLFunctions.cs
+++ b/src/NHibernate.Test/Hql/HQLFunctions.cs
@@ -1131,6 +1131,25 @@ public void Concat()
 				}
 			}
 		}
+		
+		[Test]
+		public void ConcatWithNull()
+		{
+			AssumeFunctionSupported("concat");
+			using (var s = OpenSession())
+			{
+				var a1 = new Animal("abcdef", 1f);
+				s.Save(a1);
+				s.Flush();
+			}
+
+			using (var s = OpenSession())
+			{
+				var hql = "select concat(a.Description,null) from Animal a";
+				var lresult = s.CreateQuery(hql).List<string>();
+				Assert.That(lresult[0], Is.EqualTo("abcdef"));
+			}
+		}
 
 		[Test]
 		public void HourMinuteSecond()
diff --git a/src/NHibernate.Test/TestDialects/SapSQLAnywhere17TestDialect.cs b/src/NHibernate.Test/TestDialects/SapSQLAnywhere17TestDialect.cs
index 35a35092ce3..a6b4c0718b2 100644
--- a/src/NHibernate.Test/TestDialects/SapSQLAnywhere17TestDialect.cs
+++ b/src/NHibernate.Test/TestDialects/SapSQLAnywhere17TestDialect.cs
@@ -30,12 +30,10 @@ public SapSQLAnywhere17TestDialect(Dialect.Dialect dialect)
 
 		/// <inheritdoc />
 		/// <remarks>
-		/// SQL Anywhere treats string parameters concatenation as yielding <c>numeric</c> and fails casting
-		/// the actual string value if it is not castable to a number. Likewise, in <c>case when</c>
-		/// statement, it treats them as yielding <c>integer</c> if all case yields parameter values, whatever
-		/// the actual type of the parameters. And in case of <c>numeric</c> computations with a <c>numeric</c>
-		/// parameter, the result is treated as a fractional digit lossy <c>double<c> instead of being kept
-		/// <c>numeric</c>. See https://stackoverflow.com/q/52558715/1178314.
+		/// SQL Anywhere treats parameters in <c>case when</c> statement as yielding <c>integer</c> if all case yields
+		/// parameter values, whatever the actual type of the parameters. And in case of <c>numeric</c> computations
+		/// with a <c>numeric</c> parameter, the result is treated as a fractional digit lossy <c>double<c> instead of
+		/// being kept <c>numeric</c>. See https://stackoverflow.com/q/52558715/1178314.
 		/// </remarks>
 		public override bool HasBrokenTypeInferenceOnSelectedParameters => true;
 
diff --git a/src/NHibernate/Dialect/SybaseSQLAnywhere10Dialect.cs b/src/NHibernate/Dialect/SybaseSQLAnywhere10Dialect.cs
index 290e626671f..4b7b1cf4c48 100644
--- a/src/NHibernate/Dialect/SybaseSQLAnywhere10Dialect.cs
+++ b/src/NHibernate/Dialect/SybaseSQLAnywhere10Dialect.cs
@@ -257,7 +257,6 @@ protected virtual void RegisterStringFunctions()
 			RegisterFunction("char_length", new StandardSQLFunction("char_length", NHibernateUtil.Int32));
 			RegisterFunction("compare", new VarArgsSQLFunction(NHibernateUtil.Int32, "compare(", ",", ")"));
 			RegisterFunction("compress", new VarArgsSQLFunction(NHibernateUtil.BinaryBlob, "compress(", ",", ")"));
-			RegisterFunction("concat", new VarArgsSQLFunction(NHibernateUtil.String, "(", "+", ")"));
 			RegisterFunction("csconvert", new VarArgsSQLFunction(NHibernateUtil.StringClob, "csconvert(", ",", ")"));
 			RegisterFunction("decompress", new VarArgsSQLFunction(NHibernateUtil.BinaryBlob, "decompress(", ",", ")"));
 			RegisterFunction("decrypt", new VarArgsSQLFunction(NHibernateUtil.BinaryBlob, "decrypt(", ",", ")"));