diff --git a/layout/generic/nsAreaFrame.cpp b/layout/generic/nsAreaFrame.cpp
index 36329806445..88c31fbb545 100644
--- a/layout/generic/nsAreaFrame.cpp
+++ b/layout/generic/nsAreaFrame.cpp
@@ -449,7 +449,8 @@ nsAreaFrame::Reflow(nsIPresContext&          aPresContext,
       aReflowState.reflowCommand->GetNext(nextFrame, PR_FALSE);
 
       // See if it's one of our absolutely positioned child frames
-      if (nextFrame && mAbsoluteFrames.ContainsFrame(nextFrame)) {
+      NS_ASSERTION(nsnull != nextFrame, "next frame in reflow command is null."); 
+      if (mAbsoluteFrames.ContainsFrame(nextFrame)) {
         // Remove the next frame from the reflow path
         aReflowState.reflowCommand->GetNext(nextFrame, PR_TRUE);
 
diff --git a/layout/html/base/src/nsAreaFrame.cpp b/layout/html/base/src/nsAreaFrame.cpp
index 36329806445..88c31fbb545 100644
--- a/layout/html/base/src/nsAreaFrame.cpp
+++ b/layout/html/base/src/nsAreaFrame.cpp
@@ -449,7 +449,8 @@ nsAreaFrame::Reflow(nsIPresContext&          aPresContext,
       aReflowState.reflowCommand->GetNext(nextFrame, PR_FALSE);
 
       // See if it's one of our absolutely positioned child frames
-      if (nextFrame && mAbsoluteFrames.ContainsFrame(nextFrame)) {
+      NS_ASSERTION(nsnull != nextFrame, "next frame in reflow command is null."); 
+      if (mAbsoluteFrames.ContainsFrame(nextFrame)) {
         // Remove the next frame from the reflow path
         aReflowState.reflowCommand->GetNext(nextFrame, PR_TRUE);