diff --git a/scripts/update-known-hosts.php b/scripts/update-known-hosts.php
index 3099daa9c9..7671b27b23 100755
--- a/scripts/update-known-hosts.php
+++ b/scripts/update-known-hosts.php
@@ -61,6 +61,7 @@
                 $scannedHosts[$host] = trim($scanner->getOutput());
             } else {
                 $stdErr->writeln(sprintf('Failed to scan host %s: %s', $host, $scanner->getErrorOutput()));
+                exit(1);
             }
             unset($scanners[$host]);
         }