diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 8ba45d2430bc..2c5dbdfd6132 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -7668,7 +7668,7 @@ UpdateViewsForTree(nsIFrame* aFrame, nsIViewManager* aViewManager,
           do {
             DoApplyRenderingChangeToTree(outOfFlowFrame, aViewManager,
                                          aFrameManager, aChange);
-          } while (outOfFlowFrame = outOfFlowFrame->GetNextContinuation());
+          } while ((outOfFlowFrame = outOfFlowFrame->GetNextContinuation()));
         } else if (childList == nsGkAtoms::popupList) {
           DoApplyRenderingChangeToTree(child, aViewManager,
                                        aFrameManager, aChange);
diff --git a/layout/base/nsFrameManager.cpp b/layout/base/nsFrameManager.cpp
index 07c6b6d5802c..759d7249dcfd 100644
--- a/layout/base/nsFrameManager.cpp
+++ b/layout/base/nsFrameManager.cpp
@@ -778,7 +778,7 @@ nsFrameManager::ReparentStyleContext(nsIFrame* aFrame)
     NS_ASSERTION(outOfFlow, "no out-of-flow frame");
     do {
       ReparentStyleContext(outOfFlow);
-    } while (outOfFlow = outOfFlow->GetNextContinuation());
+    } while ((outOfFlow = outOfFlow->GetNextContinuation()));
   }
 
   // DO NOT verify the style tree before reparenting.  The frame
@@ -1498,7 +1498,7 @@ nsFrameManager::ReResolveStyleContext(nsPresContext     *aPresContext,
                                       aRestyleTracker,
                                       kidsDesiredA11yNotification,
                                       aVisibleKidsOfHiddenElement);
-              } while (outOfFlowFrame = outOfFlowFrame->GetNextContinuation());
+              } while ((outOfFlowFrame = outOfFlowFrame->GetNextContinuation()));
 
               // reresolve placeholder's context under the same parent
               // as the out-of-flow frame