diff --git a/features/site.feature b/features/site.feature
index 7f343d42..c27b9b34 100644
--- a/features/site.feature
+++ b/features/site.feature
@@ -120,6 +120,29 @@ Feature: Manage sites in a multisite installation
     When I try the previous command again
     Then the return code should be 1
 
+    When I run `wp site create --slug=42`
+    Then STDOUT should contain:
+      """
+      Success: Site 3 created: http
+      """
+    And STDOUT should contain:
+      """
+      ://example.com/42/
+      """
+
+    When I run `wp site delete --slug=42 --yes`
+    Then STDOUT should contain:
+      """
+      ://example.com/42/' was deleted.
+      """
+
+    When I try the previous command again
+    Then STDERR should contain:
+      """
+      Site with slug '42' does not exist.
+      """
+    And the return code should be 1
+
   Scenario: Get site info
     Given a WP multisite install
 
diff --git a/src/Site_Command.php b/src/Site_Command.php
index a802264f..b06a7909 100644
--- a/src/Site_Command.php
+++ b/src/Site_Command.php
@@ -332,7 +332,11 @@ public function delete( $args, $assoc_args ) {
 		}
 
 		if ( isset( $assoc_args['slug'] ) ) {
-			$blog = get_blog_details( trim( $assoc_args['slug'], '/' ) );
+			$blog_id = get_id_from_blogname( $assoc_args['slug'] );
+			if ( null === $blog_id ) {
+				WP_CLI::error( "Site with slug '{$assoc_args['slug']}' does not exist." );
+			}
+			$blog = get_blog_details( $blog_id );
 		} else {
 			if ( empty( $args ) ) {
 				WP_CLI::error( 'Need to specify a blog id.' );