diff --git a/tests/EndToEnd/general/uninstall/UninstallCest.php b/tests/EndToEnd/general/uninstall/UninstallCest.php
index 2ae1cc343..ad968104c 100644
--- a/tests/EndToEnd/general/uninstall/UninstallCest.php
+++ b/tests/EndToEnd/general/uninstall/UninstallCest.php
@@ -63,8 +63,10 @@ public function testPluginDeletionRevokesAndRemovesTokens(EndToEndTester $I)
 		// Delete the Plugin.
 		$I->deleteKitPlugin($I);
 
+		// Allow the uninstallation routine time to complete.
+		$I->wait(10);
+
 		// Confirm the credentials have been removed from the Plugin's settings.
-		$I->wait(3);
 		$settings = $I->grabOptionFromDatabase('_wp_convertkit_settings');
 		$I->assertEmpty($settings['access_token']);
 		$I->assertEmpty($settings['refresh_token']);
diff --git a/uninstall.php b/uninstall.php
index ac47f35cd..b89185b36 100644
--- a/uninstall.php
+++ b/uninstall.php
@@ -30,14 +30,12 @@
 		'https://api.kit.com/v4/oauth/revoke',
 		array(
 			'headers' => array(
-				'Accept'       => 'application/json',
-				'Content-Type' => 'application/json',
+				'Content-Type' => 'application/x-www-form-urlencoded',
 			),
-			'body'    => wp_json_encode(
-				array(
-					'client_id' => 'HXZlOCj-K5r0ufuWCtyoyo3f688VmMAYSsKg1eGvw0Y',
-					'token'     => $settings['access_token'],
-				)
+			'body'    => array(
+				'client_id'       => 'HXZlOCj-K5r0ufuWCtyoyo3f688VmMAYSsKg1eGvw0Y',
+				'token'           => $settings['access_token'],
+				'token_type_hint' => 'access_token',
 			),
 			'timeout' => 5,
 		)
@@ -50,14 +48,12 @@
 		'https://api.kit.com/v4/oauth/revoke',
 		array(
 			'headers' => array(
-				'Accept'       => 'application/json',
-				'Content-Type' => 'application/json',
+				'Content-Type' => 'application/x-www-form-urlencoded',
 			),
-			'body'    => wp_json_encode(
-				array(
-					'client_id' => 'HXZlOCj-K5r0ufuWCtyoyo3f688VmMAYSsKg1eGvw0Y',
-					'token'     => $settings['refresh_token'],
-				)
+			'body'    => array(
+				'client_id'       => 'HXZlOCj-K5r0ufuWCtyoyo3f688VmMAYSsKg1eGvw0Y',
+				'token'           => $settings['refresh_token'],
+				'token_type_hint' => 'refresh_token',
 			),
 			'timeout' => 5,
 		)