diff --git a/blocks/library/latest-posts/index.js b/blocks/library/latest-posts/index.js
index 6e4e865ea5b27..7ccdc7a2ee2aa 100644
--- a/blocks/library/latest-posts/index.js
+++ b/blocks/library/latest-posts/index.js
@@ -36,28 +36,6 @@ registerBlockType( 'core/latest-posts', {
 
 	keywords: [ __( 'recent posts' ) ],
 
-	attributes: {
-		postsToShow: {
-			type: 'number',
-			default: 5,
-		},
-		displayPostDate: {
-			type: 'boolean',
-			default: false,
-		},
-		layout: {
-			type: 'string',
-			default: 'list',
-		},
-		columns: {
-			type: 'number',
-			default: 3,
-		},
-		align: {
-			type: 'string',
-		},
-	},
-
 	getEditWrapperProps( attributes ) {
 		const { align } = attributes;
 		if ( 'left' === align || 'right' === align || 'wide' === align || 'full' === align ) {
diff --git a/blocks/library/latest-posts/index.php b/blocks/library/latest-posts/index.php
index 978f1374da40e..9335cdebdae7d 100644
--- a/blocks/library/latest-posts/index.php
+++ b/blocks/library/latest-posts/index.php
@@ -13,27 +13,8 @@
  * @return string Returns the post content with latest posts added.
  */
 function gutenberg_render_block_core_latest_posts( $attributes ) {
-	$posts_to_show = 5;
-
-	if ( array_key_exists( 'postsToShow', $attributes ) ) {
-
-		// Basic attribute validation.
-		if (
-			is_numeric( $attributes['postsToShow'] ) &&
-			$attributes['postsToShow'] > 0 &&
-			$attributes['postsToShow'] < 100
-		) {
-			$posts_to_show = intval( $attributes['postsToShow'] );
-		}
-	}
-
-	$align = 'center';
-	if ( isset( $attributes['align'] ) && in_array( $attributes['align'], array( 'left', 'right', 'wide', 'full' ), true ) ) {
-		$align = $attributes['align'];
-	}
-
 	$recent_posts = wp_get_recent_posts( array(
-		'numberposts' => $posts_to_show,
+		'numberposts' => $attributes['postsToShow'],
 		'post_status' => 'publish',
 	) );
 
@@ -63,7 +44,7 @@ function gutenberg_render_block_core_latest_posts( $attributes ) {
 		$list_items_markup .= "</li>\n";
 	}
 
-	$class = "wp-block-latest-posts align{$align}";
+	$class = "wp-block-latest-posts align{$attributes['align']}";
 	if ( isset( $attributes['layout'] ) && 'grid' === $attributes['layout'] ) {
 		$class .= ' is-grid';
 	}
@@ -82,5 +63,28 @@ function gutenberg_render_block_core_latest_posts( $attributes ) {
 }
 
 register_block_type( 'core/latest-posts', array(
+	'attributes' => array(
+		'postsToShow' => array(
+			'type' => 'number',
+			'default' => 5,
+		),
+		'displayPostDate' => array(
+			'type' => 'boolean',
+			'default' => false,
+		),
+		'layout' => array(
+			'type' => 'string',
+			'default' => 'list',
+		),
+		'columns' => array(
+			'type' => 'number',
+			'default' => 3,
+		),
+		'align' => array(
+			'type' => 'string',
+			'default' => 'center',
+		),
+	),
+
 	'render_callback' => 'gutenberg_render_block_core_latest_posts',
 ) );
diff --git a/blocks/test/fixtures/core__latest-posts.json b/blocks/test/fixtures/core__latest-posts.json
index c1e9e6f8d4433..8f17313f15f96 100644
--- a/blocks/test/fixtures/core__latest-posts.json
+++ b/blocks/test/fixtures/core__latest-posts.json
@@ -7,7 +7,8 @@
             "postsToShow": 5,
             "displayPostDate": false,
             "layout": "list",
-            "columns": 3
+            "columns": 3,
+            "align": "center"
         }
     }
 ]
diff --git a/blocks/test/fixtures/core__latest-posts__displayPostDate.json b/blocks/test/fixtures/core__latest-posts__displayPostDate.json
index 238718c80ea86..58ed17cb9dc05 100644
--- a/blocks/test/fixtures/core__latest-posts__displayPostDate.json
+++ b/blocks/test/fixtures/core__latest-posts__displayPostDate.json
@@ -7,7 +7,8 @@
             "postsToShow": 5,
             "displayPostDate": true,
             "layout": "list",
-            "columns": 3
+            "columns": 3,
+            "align": "center"
         }
     }
 ]
diff --git a/blocks/test/server-attributes.json b/blocks/test/server-attributes.json
index 0967ef424bce6..ffbc5ddd6aad9 100644
--- a/blocks/test/server-attributes.json
+++ b/blocks/test/server-attributes.json
@@ -1 +1,24 @@
-{}
+{
+    "core\/latest-posts": {
+        "postsToShow": {
+            "type": "number",
+            "default": 5
+        },
+        "displayPostDate": {
+            "type": "boolean",
+            "default": false
+        },
+        "layout": {
+            "type": "string",
+            "default": "list"
+        },
+        "columns": {
+            "type": "number",
+            "default": 3
+        },
+        "align": {
+            "type": "string",
+            "default": "center"
+        }
+    }
+}
\ No newline at end of file