diff --git a/src/Hl7.Fhir.Conformance/Model/Generated/ElementDefinition.cs b/src/Hl7.Fhir.Conformance/Model/Generated/ElementDefinition.cs
index b6ea5165a4..cc1843ebed 100644
--- a/src/Hl7.Fhir.Conformance/Model/Generated/ElementDefinition.cs
+++ b/src/Hl7.Fhir.Conformance/Model/Generated/ElementDefinition.cs
@@ -1401,6 +1401,8 @@ public string Key
       /// Why this constraint is necessary or appropriate
       /// </summary>
       [FhirElement("requirements", InSummary=true, Order=40)]
+      [DeclaredType(Type = typeof(FhirString))]
+      [DeclaredType(Type = typeof(Markdown), Since = FhirRelease.R5)]
       [DataMember]
       public Hl7.Fhir.Model.Markdown Requirements
       {
@@ -2113,6 +2115,8 @@ public Hl7.Fhir.Model.BindingStrength? Strength
       /// Intended use of codes in the bound value set
       /// </summary>
       [FhirElement("description", InSummary=true, Order=40)]
+      [DeclaredType(Type = typeof(FhirString))]
+      [DeclaredType(Type = typeof(Markdown), Since = FhirRelease.R5)]
       [DataMember]
       public Hl7.Fhir.Model.Markdown Description
       {
@@ -2684,6 +2688,8 @@ public string Map
       /// Comments about the mapping or its use
       /// </summary>
       [FhirElement("comment", InSummary=true, Order=60)]
+      [DeclaredType(Type = typeof(FhirString))]
+      [DeclaredType(Type = typeof(Markdown), Since = FhirRelease.R5)]
       [DataMember]
       public Hl7.Fhir.Model.Markdown Comment
       {
diff --git a/src/Hl7.Fhir.R5.Tests/Hl7.Fhir.R5.Tests.csproj b/src/Hl7.Fhir.R5.Tests/Hl7.Fhir.R5.Tests.csproj
index 6460da7b5b..7444d7d7f1 100644
--- a/src/Hl7.Fhir.R5.Tests/Hl7.Fhir.R5.Tests.csproj
+++ b/src/Hl7.Fhir.R5.Tests/Hl7.Fhir.R5.Tests.csproj
@@ -4,6 +4,10 @@
 
 	<Import Project="..\firely-net-sdk-tests.props" />
 
+	<PropertyGroup>
+		<DefineConstants>R5</DefineConstants>
+	</PropertyGroup>
+
 	<PropertyGroup>
 		<AssemblyName>Hl7.Fhir.R5.Tests</AssemblyName>
 	</PropertyGroup>
diff --git a/src/Hl7.Fhir.STU3/Model/Generated/ElementDefinition.cs b/src/Hl7.Fhir.STU3/Model/Generated/ElementDefinition.cs
index 20cdc0a6d7..a442624643 100644
--- a/src/Hl7.Fhir.STU3/Model/Generated/ElementDefinition.cs
+++ b/src/Hl7.Fhir.STU3/Model/Generated/ElementDefinition.cs
@@ -1346,6 +1346,8 @@ public string Key
       /// Why this constraint is necessary or appropriate
       /// </summary>
       [FhirElement("requirements", InSummary=true, Order=40)]
+      [DeclaredType(Type = typeof(FhirString))]
+      [DeclaredType(Type = typeof(Markdown), Since = FhirRelease.R5)]
       [DataMember]
       public Hl7.Fhir.Model.FhirString RequirementsElement
       {
@@ -1720,6 +1722,8 @@ public Hl7.Fhir.Model.BindingStrength? Strength
       /// Human explanation of the value set
       /// </summary>
       [FhirElement("description", InSummary=true, Order=40)]
+      [DeclaredType(Type = typeof(FhirString))]
+      [DeclaredType(Type = typeof(Markdown), Since = FhirRelease.R5)]
       [DataMember]
       public Hl7.Fhir.Model.FhirString DescriptionElement
       {
@@ -1976,6 +1980,8 @@ public string Map
       /// Comments about the mapping or its use
       /// </summary>
       [FhirElement("comment", InSummary=true, Order=60)]
+      [DeclaredType(Type = typeof(FhirString))]
+      [DeclaredType(Type = typeof(Markdown), Since = FhirRelease.R5)]
       [DataMember]
       public Hl7.Fhir.Model.FhirString CommentElement
       {
diff --git a/src/Hl7.Fhir.Shared.Tests/ElementModel/PocoTypedElementTests.cs b/src/Hl7.Fhir.Shared.Tests/ElementModel/PocoTypedElementTests.cs
index 8ff6be4031..1db0e1aaab 100644
--- a/src/Hl7.Fhir.Shared.Tests/ElementModel/PocoTypedElementTests.cs
+++ b/src/Hl7.Fhir.Shared.Tests/ElementModel/PocoTypedElementTests.cs
@@ -1,4 +1,5 @@
-using Hl7.Fhir.ElementModel;
+using FluentAssertions;
+using Hl7.Fhir.ElementModel;
 using Hl7.Fhir.FhirPath;
 using Hl7.Fhir.Model;
 using Hl7.Fhir.Serialization;
@@ -191,5 +192,41 @@ public async Tasks.Task ValidateFiveWs()
 
             Assert.AreEqual(poco.Subject, subjectProp);
         }
+
+
+        [TestMethod]
+        public void CheckTypeOfElementDefinitionMembers()
+        {
+#if !R5
+            var resultType = "string";
+#else
+            var resultType = "markdown";
+#endif
+            var ed = new ElementDefinition()
+            {
+                Mapping = new System.Collections.Generic.List<ElementDefinition.MappingComponent>() {
+                            new ElementDefinition.MappingComponent() {
+                                Comment = "comment"
+                                }
+                            },
+                Binding = new ElementDefinition.ElementDefinitionBindingComponent()
+                {
+                    Description = "description",
+
+                },
+                Constraint = new System.Collections.Generic.List<ElementDefinition.ConstraintComponent>()
+                {
+                    new ElementDefinition.ConstraintComponent()
+                    {
+                        Requirements = "requirements"
+                    }
+                }
+            };
+            var element = ed.ToTypedElement();
+            element.Select("mapping.comment").First().InstanceType.Should().Be(resultType);
+            element.Select("binding.description").First().InstanceType.Should().Be(resultType);
+            element.Select("constraint.requirements").First().InstanceType.Should().Be(resultType);
+        }
+
     }
 }