diff --git a/packages/core/src/types/span.ts b/packages/core/src/types/span.ts
index 1e44809a8fa0..7a7cddba62fa 100644
--- a/packages/core/src/types/span.ts
+++ b/packages/core/src/types/span.ts
@@ -61,7 +61,7 @@ export interface StreamedSpanJSON {
  * Main difference: Attributes are converted to {@link Attributes}, thus including the `type` annotation.
  */
 export type SerializedStreamedSpan = Omit<StreamedSpanJSON, 'attributes' | 'links'> & {
-  attributes?: Attributes;
+  attributes: Attributes;
   links?: SpanLinkJSON<Attributes>[];
 };