diff --git a/mozilla/layout/html/table/src/FixedTableLayoutStrategy.cpp b/mozilla/layout/html/table/src/FixedTableLayoutStrategy.cpp
index 31c01d07342..fbc44dd6dd1 100644
--- a/mozilla/layout/html/table/src/FixedTableLayoutStrategy.cpp
+++ b/mozilla/layout/html/table/src/FixedTableLayoutStrategy.cpp
@@ -113,6 +113,7 @@ PRBool FixedTableLayoutStrategy::AssignPreliminaryColumnWidths(nscoord aComputed
     // Get column information
     nsTableColFrame* colFrame = mTableFrame->GetColFrame(colX);
     NS_ASSERTION(nsnull != colFrame, "bad col frame");
+    if (!colFrame) return PR_FALSE;
 
     // Get the columns's style
     const nsStylePosition* colPosition;
diff --git a/mozilla/layout/tables/FixedTableLayoutStrategy.cpp b/mozilla/layout/tables/FixedTableLayoutStrategy.cpp
index 31c01d07342..fbc44dd6dd1 100644
--- a/mozilla/layout/tables/FixedTableLayoutStrategy.cpp
+++ b/mozilla/layout/tables/FixedTableLayoutStrategy.cpp
@@ -113,6 +113,7 @@ PRBool FixedTableLayoutStrategy::AssignPreliminaryColumnWidths(nscoord aComputed
     // Get column information
     nsTableColFrame* colFrame = mTableFrame->GetColFrame(colX);
     NS_ASSERTION(nsnull != colFrame, "bad col frame");
+    if (!colFrame) return PR_FALSE;
 
     // Get the columns's style
     const nsStylePosition* colPosition;