diff --git a/python/dask_cudf/dask_cudf/sorting.py b/python/dask_cudf/dask_cudf/sorting.py
index 5f2af445170..e8551493bb1 100644
--- a/python/dask_cudf/dask_cudf/sorting.py
+++ b/python/dask_cudf/dask_cudf/sorting.py
@@ -224,6 +224,8 @@ def sort_values(
     na_position="last",
 ):
     """Sort by the given list/tuple of column names."""
+    if not isinstance(ascending, bool):
+        raise ValueError("ascending must be either True or False")
     if na_position not in ("first", "last"):
         raise ValueError("na_position must be either 'first' or 'last'")