diff --git a/mozilla/layout/html/table/src/BasicTableLayoutStrategy.cpp b/mozilla/layout/html/table/src/BasicTableLayoutStrategy.cpp
index f19a4bb2651..a128f01495f 100644
--- a/mozilla/layout/html/table/src/BasicTableLayoutStrategy.cpp
+++ b/mozilla/layout/html/table/src/BasicTableLayoutStrategy.cpp
@@ -212,8 +212,9 @@ BasicTableLayoutStrategy::BalanceColumnWidths(nsIPresContext*          aPresCont
 
   // determine if the table is auto/fixed and get the fixed width if available
   nscoord maxWidth = mTableFrame->CalcBorderBoxWidth(aReflowState);
-  if (NS_UNCONSTRAINEDSIZE == maxWidth) { 
-    NS_ASSERTION(PR_FALSE, "cannot balance with an unconstrained width");
+  if (NS_UNCONSTRAINEDSIZE == maxWidth) {
+    maxWidth = PR_MIN(maxWidth, aReflowState.availableWidth);
+    NS_ASSERTION(NS_UNCONSTRAINEDSIZE != maxWidth, "cannot balance with an unconstrained width");
     return PR_FALSE;
   }
   // initialize the col percent and cell percent values to 0.
diff --git a/mozilla/layout/html/table/src/nsTableFrame.cpp b/mozilla/layout/html/table/src/nsTableFrame.cpp
index 2364ded98b8..43078fde255 100644
--- a/mozilla/layout/html/table/src/nsTableFrame.cpp
+++ b/mozilla/layout/html/table/src/nsTableFrame.cpp
@@ -3935,7 +3935,7 @@ nsTableFrame::CalcBorderBoxWidth(const nsHTMLReflowState& aState)
 
   if (eStyleUnit_Auto == aState.mStylePosition->mWidth.GetUnit()) {
     if (0 == width) {
-      width = NS_UNCONSTRAINEDSIZE;
+      width = aState.availableWidth;
     }
     if (NS_UNCONSTRAINEDSIZE != aState.availableWidth) {
       nsMargin margin(0,0,0,0);
diff --git a/mozilla/layout/tables/BasicTableLayoutStrategy.cpp b/mozilla/layout/tables/BasicTableLayoutStrategy.cpp
index f19a4bb2651..a128f01495f 100644
--- a/mozilla/layout/tables/BasicTableLayoutStrategy.cpp
+++ b/mozilla/layout/tables/BasicTableLayoutStrategy.cpp
@@ -212,8 +212,9 @@ BasicTableLayoutStrategy::BalanceColumnWidths(nsIPresContext*          aPresCont
 
   // determine if the table is auto/fixed and get the fixed width if available
   nscoord maxWidth = mTableFrame->CalcBorderBoxWidth(aReflowState);
-  if (NS_UNCONSTRAINEDSIZE == maxWidth) { 
-    NS_ASSERTION(PR_FALSE, "cannot balance with an unconstrained width");
+  if (NS_UNCONSTRAINEDSIZE == maxWidth) {
+    maxWidth = PR_MIN(maxWidth, aReflowState.availableWidth);
+    NS_ASSERTION(NS_UNCONSTRAINEDSIZE != maxWidth, "cannot balance with an unconstrained width");
     return PR_FALSE;
   }
   // initialize the col percent and cell percent values to 0.
diff --git a/mozilla/layout/tables/nsTableFrame.cpp b/mozilla/layout/tables/nsTableFrame.cpp
index 2364ded98b8..43078fde255 100644
--- a/mozilla/layout/tables/nsTableFrame.cpp
+++ b/mozilla/layout/tables/nsTableFrame.cpp
@@ -3935,7 +3935,7 @@ nsTableFrame::CalcBorderBoxWidth(const nsHTMLReflowState& aState)
 
   if (eStyleUnit_Auto == aState.mStylePosition->mWidth.GetUnit()) {
     if (0 == width) {
-      width = NS_UNCONSTRAINEDSIZE;
+      width = aState.availableWidth;
     }
     if (NS_UNCONSTRAINEDSIZE != aState.availableWidth) {
       nsMargin margin(0,0,0,0);