diff --git a/py-polars/src/functions/lazy.rs b/py-polars/src/functions/lazy.rs
index 904d4813837e1..763cb01895515 100644
--- a/py-polars/src/functions/lazy.rs
+++ b/py-polars/src/functions/lazy.rs
@@ -187,6 +187,7 @@ pub fn cumreduce(lambda: PyObject, exprs: Vec<PyExpr>) -> PyExpr {
 }
 
 #[pyfunction]
+#[pyo3(signature = (year, month, day, hour=None, minute=None, second=None, microsecond=None, time_unit=Wrap(TimeUnit::Microseconds), time_zone=None))]
 pub fn datetime(
     year: PyExpr,
     month: PyExpr,
@@ -195,12 +196,14 @@ pub fn datetime(
     minute: Option<PyExpr>,
     second: Option<PyExpr>,
     microsecond: Option<PyExpr>,
+    time_unit: Wrap<TimeUnit>,
+    time_zone: Option<TimeZone>,
 ) -> PyExpr {
     let year = year.inner;
     let month = month.inner;
     let day = day.inner;
-
     set_unwrapped_or_0!(hour, minute, second, microsecond);
+    let time_unit = time_unit.0;
 
     let args = DatetimeArgs {
         year,
@@ -210,6 +213,8 @@ pub fn datetime(
         minute,
         second,
         microsecond,
+        time_unit,
+        time_zone,
     };
     dsl::datetime(args).into()
 }