diff --git a/packages/flutter/lib/src/material/overscroll_indicator.dart b/packages/flutter/lib/src/material/overscroll_indicator.dart
index 08a0b2e920..74b8d3f9f9 100644
--- a/packages/flutter/lib/src/material/overscroll_indicator.dart
+++ b/packages/flutter/lib/src/material/overscroll_indicator.dart
@@ -226,10 +226,10 @@ class _OverscrollIndicatorState extends State<OverscrollIndicator> {
       child: new AnimatedBuilder(
         animation: _extentAnimation,
         builder: (BuildContext context, Widget child) {
-          if (_scrollDirection == null) // Haven't seen a scroll yet.
-            return child;
+          // We keep the same widget hierarchy here, even when we're not
+          // painting anything, to avoid rebuilding the children.
           return new CustomPaint(
-            foregroundPainter: new _Painter(
+            foregroundPainter: _scrollDirection == null ? null : new _Painter(
               scrollDirection: _scrollDirection,
               extent: _extentAnimation.value,
               isLeading: _scrollOffset < _minScrollOffset,
diff --git a/packages/flutter/lib/src/rendering/proxy_box.dart b/packages/flutter/lib/src/rendering/proxy_box.dart
index 2986850827..e7603eecb4 100644
--- a/packages/flutter/lib/src/rendering/proxy_box.dart
+++ b/packages/flutter/lib/src/rendering/proxy_box.dart
@@ -1610,8 +1610,8 @@ class RenderCustomPaint extends RenderProxyBox {
       markNeedsPaint();
     }
     if (attached) {
-      oldPainter._repaint?.removeListener(markNeedsPaint);
-      newPainter._repaint?.addListener(markNeedsPaint);
+      oldPainter?._repaint?.removeListener(markNeedsPaint);
+      newPainter?._repaint?.addListener(markNeedsPaint);
     }
   }
 
diff --git a/packages/flutter/lib/src/widgets/clamp_overscrolls.dart b/packages/flutter/lib/src/widgets/clamp_overscrolls.dart
index bab99998dc..20eb7634c7 100644
--- a/packages/flutter/lib/src/widgets/clamp_overscrolls.dart
+++ b/packages/flutter/lib/src/widgets/clamp_overscrolls.dart
@@ -50,14 +50,18 @@ class ClampOverscrolls extends InheritedWidget {
   ///
   /// This utility function is typically used by [Scrollable.builder] callbacks.
   static Widget buildViewport(BuildContext context, ScrollableState state, ViewportBuilder builder) {
+    // TODO(ianh): minScrollOffset and maxScrollOffset are typically determined
+    // by the container and content size. But we don't know those until we
+    // layout the viewport, which happens after build phase. We need to rethink
+    // this.
     final bool clampOverscrolls = ClampOverscrolls.of(context);
     final double clampedScrollOffset = clampOverscrolls
       ? state.scrollOffset.clamp(state.scrollBehavior.minScrollOffset, state.scrollBehavior.maxScrollOffset)
       : state.scrollOffset;
-   Widget viewport = builder(context, state, clampedScrollOffset);
-   if (clampOverscrolls)
-     viewport = new ClampOverscrolls(value: false, child: viewport);
-   return viewport;
+    Widget viewport = builder(context, state, clampedScrollOffset);
+    if (clampOverscrolls)
+      viewport = new ClampOverscrolls(value: false, child: viewport);
+    return viewport;
   }
 
   @override