--- a/layout/tables/BasicTableLayoutStrategy.cpp
+++ b/layout/tables/BasicTableLayoutStrategy.cpp
@@ -694,17 +694,17 @@ BasicTableLayoutStrategy::ComputeColumnW
 
     // border-spacing isn't part of the basis for percentages.
     nscoord subtract = spacing;
     for (PRInt32 col = 0; col < colCount; ++col) {
         if (mTableFrame->GetNumCellsOriginatingInCol(col)) {
             subtract += spacing;
         }
     }
-    width -= subtract;
+    width = NSCoordSaturatingSubtract(width, subtract, nscoord_MAX);
     min -= subtract;
 
     // XXX is |width| the right basis for percentage widths?
 
     /*
      * The goal of this function is to allocate |width| to the columns
      * by making an appropriate SetFinalWidth call to each column.
      *