diff --git a/inc/functions.php b/inc/functions.php
index 42cf41bc..cd83013d 100644
--- a/inc/functions.php
+++ b/inc/functions.php
@@ -1881,6 +1881,17 @@ function checkIPAPI(string $ip): bool {
 		}
 
 		$json = json_decode($reply);
+		if ($json === null) {
+			error_log('IPHub query failed: api returned incorrect json');
+
+			if ($config['cache']['enabled']) {
+				// Store the result for 4 hours.
+				cache::set("ip_api_block_$ip", 'api_error', 14400);
+			}
+
+			return false;
+		}
+
 		if (isset($json->error)) {
 			error_log("IPHub query failed: $json->error");