diff --git a/packages/block-library/src/search/block.json b/packages/block-library/src/search/block.json
index 8d5e208045068d..05cb3f15e02b0e 100644
--- a/packages/block-library/src/search/block.json
+++ b/packages/block-library/src/search/block.json
@@ -25,7 +25,8 @@
 			"type": "number"
 		},
 		"widthUnit": {
-			"type": "string"
+			"type": "string",
+			"default": "px"
 		},
 		"buttonText": {
 			"type": "string",