diff --git a/src/transformers/generation/configuration_utils.py b/src/transformers/generation/configuration_utils.py
index 6b0b434ec726..cb9240d3bf33 100644
--- a/src/transformers/generation/configuration_utils.py
+++ b/src/transformers/generation/configuration_utils.py
@@ -410,7 +410,7 @@ def validate(self, is_init=False):
 
         # 2. detect beam-only parameterization when not in beam mode
         if self.num_beams is None:
-            logging.warning("`num_beams` is set to None - defaulting to 1.", UserWarning)
+            warnings.warn("`num_beams` is set to None - defaulting to 1.", UserWarning)
             self.num_beams = 1
 
         if self.num_beams == 1: