diff --git a/src/JsonSchemaExtractor.php b/src/JsonSchemaExtractor.php
index 984be04..fa6ceed 100644
--- a/src/JsonSchemaExtractor.php
+++ b/src/JsonSchemaExtractor.php
@@ -192,7 +192,7 @@ private static function remote_get( $url ) {
 			return '';
 		}
 
-		$headers  = [ 'Content-type: application/json' ];
+		$headers  = [ 'Content-Type' => 'application/json' ];
 		$options  = [ 'halt_on_error' => false ];
 		$response = Utils\http_request( 'GET', $url, null, $headers, $options );