diff --git a/NHibernate.Spatial.PostGis/Dialect/PostGisDialect.cs b/NHibernate.Spatial.PostGis/Dialect/PostGisDialect.cs
index 1e14001e..88f97b4e 100644
--- a/NHibernate.Spatial.PostGis/Dialect/PostGisDialect.cs
+++ b/NHibernate.Spatial.PostGis/Dialect/PostGisDialect.cs
@@ -445,9 +445,32 @@ protected string GetSpatialCreateString(string schema, string prefix)
         {
             // Intersection aggregate function by Mark Fenbers
             // See http://postgis.refractions.net/pipermail/postgis-users/2005-May/008156.html
-            string script = string.Format(
-                "DROP AGGREGATE IF EXISTS {0}{1}(GEOMETRY);" +
-                "CREATE AGGREGATE {0}{1}(BASETYPE=GEOMETRY, SFUNC={2}Intersection, STYPE=GEOMETRY);"
+            // NOTE: An additional paramter was added to ST_Intersection in PostGIS 3.1
+            //       https://github.com/nhibernate/NHibernate.Spatial/issues/129
+            string script = string.Format(@"
+                CREATE OR REPLACE FUNCTION {0}NHSP_CreateIntersectionAggregate()
+                RETURNS void AS $$
+                    BEGIN
+                        DROP AGGREGATE IF EXISTS {0}{1}(GEOMETRY);
+                        IF (SELECT PostGIS_Lib_Version() < '3.1') THEN
+                            CREATE AGGREGATE {0}{1}(basetype=geometry, sfunc={2}Intersection, stype=geometry);
+                        ELSE
+                            CREATE OR REPLACE FUNCTION {0}NHSP_Intersection(geometry, geometry)
+                                RETURNS geometry
+                                LANGUAGE SQL
+                                AS 'SELECT {0}{2}Intersection($1, $2)'
+                                IMMUTABLE STRICT
+                                COST 10000;
+                            CREATE AGGREGATE {0}{1}(basetype=geometry, sfunc={0}NHSP_Intersection, stype=geometry);
+                        END IF;
+                    END;
+                $$ LANGUAGE plpgsql;
+
+                -- NOTE: Cast to text required to avoid following error on PostgreSQL 9.0 and lower:
+                --       Npgsql.PostgresException : 42883: no binary output function available for type void
+                --       https://github.com/npgsql/npgsql/issues/818
+                --       https://www.postgresql.org/message-id/21459.1437692282%40sss.pgh.pa.us
+                SELECT {0}NHSP_CreateIntersectionAggregate()::text;"
                 , this.QuoteSchema(schema)
                 , IntersectionAggregateName
                 , prefix
diff --git a/Tests.NHibernate.Spatial.PostGis/PostGisConformanceItemsFixture.cs b/Tests.NHibernate.Spatial.PostGis/PostGisConformanceItemsFixture.cs
index 3ed05a85..dc979eeb 100644
--- a/Tests.NHibernate.Spatial.PostGis/PostGisConformanceItemsFixture.cs
+++ b/Tests.NHibernate.Spatial.PostGis/PostGisConformanceItemsFixture.cs
@@ -66,40 +66,5 @@ public override void ConformanceItemT31Linq()
 
             Assert.IsTrue(expected.EqualsTopologically(geometry));
         }
-
-        /// <summary>
-        /// Overridden because polygon vertices are returned in a different order in PostGIS
-        /// </summary>
-        [Test]
-        public override void ConformanceItemT48Hql()
-        {
-            string query =
-                @"select NHSP.AsText(NHSP.Difference(np.Boundary, f.Boundary))
-				from NamedPlace np, Forest f
-				where np.Name = 'Ashton' and f.Name = 'Green Forest'
-				";
-            string result = session.CreateQuery(query)
-                .UniqueResult<string>();
-
-            Geometry geometry = Wkt.Read(result);
-            Geometry expected = Wkt.Read("POLYGON ((62 48, 84 48, 84 42, 56 34, 62 48))");
-
-            Assert.IsTrue(expected.EqualsExact(geometry, Tolerance));
-        }
-
-        [Test]
-        public override void ConformanceItemT48Linq()
-        {
-            var query =
-                from np in session.Query<NamedPlace>()
-                from f in session.Query<Forest>()
-                where np.Name == "Ashton" && f.Name == "Green Forest"
-                select np.Boundary.Difference(f.Boundary);
-
-            Geometry geometry = query.Single();
-            Geometry expected = Wkt.Read("POLYGON ((62 48, 84 48, 84 42, 56 34, 62 48))");
-
-            Assert.IsTrue(expected.EqualsExact(geometry, Tolerance));
-        }
     }
 }
diff --git a/Tests.NHibernate.Spatial/OgcSfSql11Compliance/ConformanceItemsFixture.cs b/Tests.NHibernate.Spatial/OgcSfSql11Compliance/ConformanceItemsFixture.cs
index b9689f52..1889a33f 100644
--- a/Tests.NHibernate.Spatial/OgcSfSql11Compliance/ConformanceItemsFixture.cs
+++ b/Tests.NHibernate.Spatial/OgcSfSql11Compliance/ConformanceItemsFixture.cs
@@ -2556,7 +2556,7 @@ public virtual void ConformanceItemT48Hql()
 			Geometry geometry = Wkt.Read(result);
 			Geometry expected = Wkt.Read("POLYGON( ( 56 34, 62 48, 84 48, 84 42, 56 34) )");
 
-            Assert.IsTrue(expected.EqualsExact(geometry, Tolerance));
+            Assert.IsTrue(expected.EqualsTopologically(geometry));
         }
 
         [Test]
@@ -2571,7 +2571,7 @@ public virtual void ConformanceItemT48Linq()
 			Geometry geometry = query.Single();
 			Geometry expected = Wkt.Read("POLYGON( ( 56 34, 62 48, 84 48, 84 42, 56 34) )");
 
-            Assert.IsTrue(expected.EqualsExact(geometry, Tolerance));
+            Assert.IsTrue(expected.EqualsTopologically(geometry));
         }
 
         /// <summary>