diff --git a/select_time_widget.py b/select_time_widget.py
index 028001f..00963a6 100644
--- a/select_time_widget.py
+++ b/select_time_widget.py
@@ -106,7 +106,7 @@ def render(self, name, value, attrs=None):
         if self.twelve_hr and self.meridiem_val:
             if self.meridiem_val.lower().startswith('p') and hour_val > 12 and hour_val < 24:
                 hour_val = hour_val % 12
-        elif hour_val == 0:
+        elif self.twelve_hr and hour_val == 0:
             hour_val = 12
             
         output = []