diff --git a/src/Statement.php b/src/Statement.php
index 9701d51..4253db4 100644
--- a/src/Statement.php
+++ b/src/Statement.php
@@ -152,8 +152,8 @@ private function parseErrorClickHouse(string $body)
         return false;
     }
 
-    private function hasErrorClickhouse(string $body, string $contentType): bool {
-        if (false === stripos($contentType, 'application/json')) {
+    private function hasErrorClickhouse(string $body, ?string $contentType): bool {
+        if ($contentType === null || false === stripos($contentType, 'application/json')) {
             return preg_match(self::CLICKHOUSE_ERROR_REGEX, $body) === 1;
         }