diff --git a/crates/polars-plan/src/plans/conversion/join.rs b/crates/polars-plan/src/plans/conversion/join.rs
index 53a7bbd2274a..0a073934b5d3 100644
--- a/crates/polars-plan/src/plans/conversion/join.rs
+++ b/crates/polars-plan/src/plans/conversion/join.rs
@@ -44,6 +44,7 @@ pub fn resolve_join(
     if matches!(options.args.how, JoinType::Cross) {
         polars_ensure!(left_on.len() + right_on.len() == 0, InvalidOperation: "a 'cross' join doesn't expect any join keys");
     } else {
+        polars_ensure!(left_on.len() + right_on.len() > 0, InvalidOperation: "expected join keys/predicates");
         check_join_keys(&left_on)?;
         check_join_keys(&right_on)?;
 
diff --git a/py-polars/tests/unit/operations/test_inequality_join.py b/py-polars/tests/unit/operations/test_inequality_join.py
index 242a0e1f5e8e..171b9b770410 100644
--- a/py-polars/tests/unit/operations/test_inequality_join.py
+++ b/py-polars/tests/unit/operations/test_inequality_join.py
@@ -460,3 +460,11 @@ def test_raise_on_multiple_binary_comparisons() -> None:
         df.join_where(
             df, (pl.col("id") < pl.col("id")) & (pl.col("id") >= pl.col("id"))
         )
+
+
+def test_raise_invalid_input_join_where() -> None:
+    df = pl.DataFrame({"id": [1, 2]})
+    with pytest.raises(pl.exceptions.InvalidOperationError):
+        df.join_where(
+            df
+        )