diff --git a/src/middlewared/middlewared/plugins/crypto.py b/src/middlewared/middlewared/plugins/crypto.py
index e598071ca10d..9ee79fb4daa8 100644
--- a/src/middlewared/middlewared/plugins/crypto.py
+++ b/src/middlewared/middlewared/plugins/crypto.py
@@ -823,7 +823,7 @@ def generate_builder(self, options):
                 not_valid_before
             ).not_valid_after(
                 not_valid_after
-            ).serial_number(options.get('serial') or 1)
+            ).serial_number(options.get('serial') or random.randint(1000, pow(2, 30)))
 
         if san:
             cert = cert.add_extension(san, False)