diff --git a/layout/generic/nsBlockReflowContext.cpp b/layout/generic/nsBlockReflowContext.cpp
index 28d66d069c..8d034edb9a 100644
--- a/layout/generic/nsBlockReflowContext.cpp
+++ b/layout/generic/nsBlockReflowContext.cpp
@@ -164,7 +164,8 @@ nsBlockReflowContext::ComputeCollapsedBStartMargin(const nsHTMLReflowState& aRS,
                                                availSpace);
             // Record that we're being optimistic by assuming the kid
             // has no clearance
-            if (kid->StyleDisplay()->mBreakType != NS_STYLE_CLEAR_NONE) {
+            if (kid->StyleDisplay()->mBreakType != NS_STYLE_CLEAR_NONE ||
+                !nsBlockFrame::BlockCanIntersectFloats(kid)) {
               *aMayNeedRetry = true;
             }
             if (ComputeCollapsedBStartMargin(innerReflowState, aMargin,