diff --git a/orangecontrib/survival_analysis/widgets/owkaplanmeier.py b/orangecontrib/survival_analysis/widgets/owkaplanmeier.py
index 4143867..77a5842 100644
--- a/orangecontrib/survival_analysis/widgets/owkaplanmeier.py
+++ b/orangecontrib/survival_analysis/widgets/owkaplanmeier.py
@@ -35,7 +35,7 @@ def generate_curve_coordinates(timeline, probabilities):
         return np.array(x), np.array(y)
 
     def __init__(self, time, events, label=None, color=None):
-        self._kmf = KaplanMeierFitter().fit(time, events)
+        self._kmf = KaplanMeierFitter().fit(time.astype(np.float64), events.astype(np.float64))
 
         self.label: str = label
         self.color: List[int] = color