diff --git a/system/HTTP/CURLRequest.php b/system/HTTP/CURLRequest.php
index e51d957e5800..90261a2d051a 100644
--- a/system/HTTP/CURLRequest.php
+++ b/system/HTTP/CURLRequest.php
@@ -650,7 +650,7 @@ protected function setCURLOptions(array $curlOptions = [], array $config = [])
         }
 
         // Resolve IP
-        if (array_key_exists('force_ip_resolve', $config) && $config['force_ip_resolve']) {
+        if (array_key_exists('force_ip_resolve', $config) && is_string($config['force_ip_resolve']) && $config['force_ip_resolve'] !== '') {
             $protocolVersion = $config['force_ip_resolve'];
 
             if ($protocolVersion === 'v4') {