diff --git a/Swan.Tiny/Formatters/Json.Converter.cs b/Swan.Tiny/Formatters/Json.Converter.cs
index 6878bcb..95b8579 100644
--- a/Swan.Tiny/Formatters/Json.Converter.cs
+++ b/Swan.Tiny/Formatters/Json.Converter.cs
@@ -75,7 +75,7 @@ namespace Swan.Formatters {
       private Object GetSourcePropertyValue(IDictionary<String, Object> sourceProperties, MemberInfo targetProperty) {
         String targetPropertyName = MemberInfoNameCache.GetOrAdd(targetProperty, x => AttributeCache.DefaultCache.Value.RetrieveOne<JsonPropertyAttribute>(x)?.PropertyName ?? x.Name.GetNameWithCase(this._jsonSerializerCase));
 
-        return sourceProperties.GetValueOrDefault(targetPropertyName);
+        return sourceProperties!.GetValueOrDefault(targetPropertyName)!;
       }
 
       private Boolean TrySetInstance(Object? targetInstance, Object source, ref Object? target) {