diff --git a/layout/html/table/src/nsTableFrame.cpp b/layout/html/table/src/nsTableFrame.cpp
index 1608d75472ae..a280179bd911 100644
--- a/layout/html/table/src/nsTableFrame.cpp
+++ b/layout/html/table/src/nsTableFrame.cpp
@@ -2530,6 +2530,7 @@ NS_METHOD nsTableFrame::IncrementalReflow(nsIPresContext* aPresContext,
       // Get the next frame in the reflow chain
       nsIFrame* nextFrame;
       reflowState.reflowCommand->GetNext(nextFrame);
+      NS_ASSERTION(nextFrame, "next frame in reflow command is null"); 
 
       // Recover our reflow state
       rv = IR_TargetIsChild(aPresContext, aDesiredSize, state, aStatus, nextFrame);
diff --git a/layout/html/table/src/nsTableOuterFrame.cpp b/layout/html/table/src/nsTableOuterFrame.cpp
index 7b11fd3f5a7a..d8082427efb2 100644
--- a/layout/html/table/src/nsTableOuterFrame.cpp
+++ b/layout/html/table/src/nsTableOuterFrame.cpp
@@ -327,6 +327,7 @@ nsresult nsTableOuterFrame::IncrementalReflow(nsIPresContext*        aPresContex
       // Get the next frame in the reflow chain
       nsIFrame* nextFrame;
       aReflowState.reflowState.reflowCommand->GetNext(nextFrame);
+      NS_ASSERTION(nextFrame, "next frame in reflow command is null"); 
 
       // Recover our reflow state
       RecoverState(aReflowState, nextFrame);
diff --git a/layout/tables/nsTableFrame.cpp b/layout/tables/nsTableFrame.cpp
index 1608d75472ae..a280179bd911 100644
--- a/layout/tables/nsTableFrame.cpp
+++ b/layout/tables/nsTableFrame.cpp
@@ -2530,6 +2530,7 @@ NS_METHOD nsTableFrame::IncrementalReflow(nsIPresContext* aPresContext,
       // Get the next frame in the reflow chain
       nsIFrame* nextFrame;
       reflowState.reflowCommand->GetNext(nextFrame);
+      NS_ASSERTION(nextFrame, "next frame in reflow command is null"); 
 
       // Recover our reflow state
       rv = IR_TargetIsChild(aPresContext, aDesiredSize, state, aStatus, nextFrame);
diff --git a/layout/tables/nsTableOuterFrame.cpp b/layout/tables/nsTableOuterFrame.cpp
index 7b11fd3f5a7a..d8082427efb2 100644
--- a/layout/tables/nsTableOuterFrame.cpp
+++ b/layout/tables/nsTableOuterFrame.cpp
@@ -327,6 +327,7 @@ nsresult nsTableOuterFrame::IncrementalReflow(nsIPresContext*        aPresContex
       // Get the next frame in the reflow chain
       nsIFrame* nextFrame;
       aReflowState.reflowState.reflowCommand->GetNext(nextFrame);
+      NS_ASSERTION(nextFrame, "next frame in reflow command is null"); 
 
       // Recover our reflow state
       RecoverState(aReflowState, nextFrame);