diff --git a/docs/reference-guides/data/data-core-editor.md b/docs/reference-guides/data/data-core-editor.md
index 43fba216c4ce08..3191956f8d99b0 100644
--- a/docs/reference-guides/data/data-core-editor.md
+++ b/docs/reference-guides/data/data-core-editor.md
@@ -218,7 +218,7 @@ _Parameters_
 
 _Returns_
 
--   `?number`: ID of current post.
+-   `?(number|string)`: The current post ID (number) or template slug (string).
 
 ### getCurrentPostLastRevisionId
 
diff --git a/packages/editor/src/store/selectors.js b/packages/editor/src/store/selectors.js
index 7f2f22d2978b4b..435eab23f0b878 100644
--- a/packages/editor/src/store/selectors.js
+++ b/packages/editor/src/store/selectors.js
@@ -195,7 +195,7 @@ export function getCurrentPostType( state ) {
  *
  * @param {Object} state Global application state.
  *
- * @return {?number} ID of current post.
+ * @return {?(number|string)} The current post ID (number) or template slug (string).
  */
 export function getCurrentPostId( state ) {
 	return state.postId;