diff --git a/tempest/common/generator/valid_generator.py b/tempest/common/generator/valid_generator.py
index a99bbc0..0d7b398 100644
--- a/tempest/common/generator/valid_generator.py
+++ b/tempest/common/generator/valid_generator.py
@@ -24,7 +24,7 @@
     @base.generator_type("string")
     @base.simple_generator
     def generate_valid_string(self, schema):
-        size = schema.get("minLength", 0)
+        size = schema.get("minLength", 1)
         # TODO(dkr mko): handle format and pattern
         return "x" * size