diff --git a/py-polars/polars/series/series.py b/py-polars/polars/series/series.py
index c66d1f0a4abc..be3734f8e7ca 100644
--- a/py-polars/polars/series/series.py
+++ b/py-polars/polars/series/series.py
@@ -3695,7 +3695,7 @@ def is_infinite(self) -> Series:
 
     def is_nan(self) -> Series:
         """
-        Returns a boolean Series indicating which values are not NaN.
+        Returns a boolean Series indicating which values are NaN.
 
         Returns
         -------