diff --git a/piker/ui/_curve.py b/piker/ui/_curve.py
index c9ebebcd..358d4844 100644
--- a/piker/ui/_curve.py
+++ b/piker/ui/_curve.py
@@ -407,9 +407,6 @@ class Curve(FlowGraphic):
 # (via it's max / min) even when highly zoomed out.
 class FlattenedOHLC(Curve):
 
-    # avoids strange dragging/smearing artifacts when panning..
-    cache_mode: int = QGraphicsItem.NoCache
-
     def draw_last_datum(
         self,
         path: QPainterPath,
@@ -435,6 +432,11 @@ class FlattenedOHLC(Curve):
 
 class StepCurve(Curve):
 
+    # avoids strange dragging/smearing artifacts when panning
+    # as well as mouse over artefacts when the vlm chart series
+    # is "shorter" then some overlay..
+    cache_mode: int = QGraphicsItem.NoCache
+
     def declare_paintables(
         self,
     ) -> None: