diff --git a/vocabularies/Org.OData.Core.V1.json b/vocabularies/Org.OData.Core.V1.json
index 9c2078b0..68e6a0f7 100644
--- a/vocabularies/Org.OData.Core.V1.json
+++ b/vocabularies/Org.OData.Core.V1.json
@@ -652,6 +652,7 @@
         "OptionalParameterType": {
             "$Kind": "ComplexType",
             "DefaultValue": {
+                "$Type": "Edm.PrimitiveType",
                 "$Nullable": true,
                 "@Core.Description": "Default value for an optional parameter of primitive or enumeration type, using the same rules as the `cast` function in URLs.",
                 "@Core.LongDescription": "If no explicit DefaultValue is specified, the service is free on how to interpret omitting the parameter from the request. For example, a service might interpret an omitted optional parameter `KeyDate` as having the current date."
diff --git a/vocabularies/Org.OData.Core.V1.md b/vocabularies/Org.OData.Core.V1.md
index 1f83dab4..db39ea71 100644
--- a/vocabularies/Org.OData.Core.V1.md
+++ b/vocabularies/Org.OData.Core.V1.md
@@ -301,7 +301,7 @@ Any simple identifier | Any type listed in `Validation.OpenPropertyTypeConstrain
 
 Property|Type|Description
 :-------|:---|:----------
-[DefaultValue](Org.OData.Core.V1.xml#L512)|String?|Default value for an optional parameter of primitive or enumeration type, using the same rules as the `cast` function in URLs.<br>If no explicit DefaultValue is specified, the service is free on how to interpret omitting the parameter from the request. For example, a service might interpret an omitted optional parameter `KeyDate` as having the current date.
+[DefaultValue](Org.OData.Core.V1.xml#L512)|PrimitiveType?|Default value for an optional parameter of primitive or enumeration type, using the same rules as the `cast` function in URLs.<br>If no explicit DefaultValue is specified, the service is free on how to interpret omitting the parameter from the request. For example, a service might interpret an omitted optional parameter `KeyDate` as having the current date.
 
 <a name="LocalDateTime"></a>
 ## [LocalDateTime](Org.OData.Core.V1.xml#L531)
diff --git a/vocabularies/Org.OData.Core.V1.xml b/vocabularies/Org.OData.Core.V1.xml
index 086bde89..f972091f 100644
--- a/vocabularies/Org.OData.Core.V1.xml
+++ b/vocabularies/Org.OData.Core.V1.xml
@@ -509,7 +509,7 @@ Any simple identifier | Any type listed in `Validation.OpenPropertyTypeConstrain
         <Annotation Term="Core.LongDescription" String="All parameters marked as optional must come after any parameters not marked as optional. The binding parameter must not be marked as optional." />
       </Term>
       <ComplexType Name="OptionalParameterType">
-        <Property Name="DefaultValue" Type="Edm.String" Nullable="true">
+        <Property Name="DefaultValue" Type="Edm.PrimitiveType" Nullable="true">
           <Annotation Term="Core.Description" String="Default value for an optional parameter of primitive or enumeration type, using the same rules as the `cast` function in URLs." />
           <Annotation Term="Core.LongDescription" String="If no explicit DefaultValue is specified, the service is free on how to interpret omitting the parameter from the request. For example, a service might interpret an omitted optional parameter `KeyDate` as having the current date." />
         </Property>