--- a/layout/generic/nsFlexContainerFrame.cpp
+++ b/layout/generic/nsFlexContainerFrame.cpp
@@ -1782,41 +1782,46 @@ nsFlexContainerFrame::
  * Caching it prevents us from doing exponential reflows in cases of deeply
  * nested flex and scroll frames.
  *
  * We store them in the frame property table for simplicity.
  */
 struct nsFlexContainerFrame::CachedMeasuringReflowResult
 {
   LogicalSize mAvailableSize;
+  const nscoord mComputedHeight;
   const nscoord mHeight;
   const nscoord mAscent;
 
   CachedMeasuringReflowResult(const LogicalSize& aAvailableSize,
+                              nscoord aComputedHeight,
                               nscoord aHeight,
                               nscoord aAscent)
     : mAvailableSize(aAvailableSize)
+    , mComputedHeight(aComputedHeight)
     , mHeight(aHeight)
     , mAscent(aAscent)
   {}
 };
 
 NS_DECLARE_FRAME_PROPERTY_DELETABLE(CachedFlexMeasuringReflow,
                                     CachedMeasuringReflowResult);
 
 const CachedMeasuringReflowResult&
 nsFlexContainerFrame::MeasureAscentAndHeightForFlexItem(
   FlexItem& aItem,
   nsPresContext* aPresContext,
   ReflowInput& aChildReflowInput)
 {
   const auto availableSize = aChildReflowInput.AvailableSize();
   const FrameProperties props = aItem.Frame()->Properties();
+  const nscoord computedHeight = aChildReflowInput.ComputedHeight();
   if (const auto* cachedResult = props.Get(CachedFlexMeasuringReflow())) {
-    if (cachedResult->mAvailableSize == availableSize) {
+    if (cachedResult->mAvailableSize == availableSize &&
+        cachedResult->mComputedHeight == computedHeight) {
       return *cachedResult;
     }
   }
 
   ReflowOutput childDesiredSize(aChildReflowInput);
   nsReflowStatus childReflowStatus;
 
   const uint32_t flags = NS_FRAME_NO_MOVE_FRAME;
@@ -1834,16 +1839,17 @@ nsFlexContainerFrame::MeasureAscentAndHe
 
   // Tell the child we're done with its initial reflow.
   // (Necessary for e.g. GetBaseline() to work below w/out asserting)
   FinishReflowChild(aItem.Frame(), aPresContext,
                     childDesiredSize, &aChildReflowInput, 0, 0, flags);
 
   auto result =
     new CachedMeasuringReflowResult(availableSize,
+                                    computedHeight,
                                     childDesiredSize.Height(),
                                     childDesiredSize.BlockStartAscent());
 
   props.Set(CachedFlexMeasuringReflow(), result);
   return *result;
 }
 
 /* virtual */ void