diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
index 5bdcb6c6a64f..205f75db493b 100644
--- a/lib/matplotlib/backend_bases.py
+++ b/lib/matplotlib/backend_bases.py
@@ -1403,7 +1403,7 @@ class MouseEvent(LocationEvent):
            last change of keyboard state occurred while the canvas did not have
            focus, this attribute will be wrong.
 
-    step : int
+    step : float
         The number of scroll steps (positive for 'up', negative for 'down').
         This applies only to 'scroll_event' and defaults to 0 otherwise.