diff --git a/pandas/_libs/tslibs/np_datetime.pyi b/pandas/_libs/tslibs/np_datetime.pyi
index c42bc43ac9d89..5a4ba673dbeff 100644
--- a/pandas/_libs/tslibs/np_datetime.pyi
+++ b/pandas/_libs/tslibs/np_datetime.pyi
@@ -19,3 +19,7 @@ def is_unitless(dtype: np.dtype) -> bool: ...
 def compare_mismatched_resolutions(
     left: np.ndarray, right: np.ndarray, op
 ) -> npt.NDArray[np.bool_]: ...
+def add_overflowsafe(
+    left: npt.NDArray[np.int64],
+    right: npt.NDArray[np.int64],
+) -> npt.NDArray[np.int64]: ...