diff --git a/mozilla/layout/generic/nsFrameSetFrame.cpp b/mozilla/layout/generic/nsFrameSetFrame.cpp
index c23f4736ee4..eddaefe3e9b 100644
--- a/mozilla/layout/generic/nsFrameSetFrame.cpp
+++ b/mozilla/layout/generic/nsFrameSetFrame.cpp
@@ -693,7 +693,9 @@ nsHTMLFramesetFrame::ParseRowColSpec(nsString&       aSpec,
   static const PRUnichar PERCENT('%');
   static const PRUnichar COMMA(',');
 
-  aSpec.Trim(" \n\r\t"); // remove leading and trailing whitespace  
+  // remove leading and trailing whitespace
+  // also remove leading/trialing commas (bug 31482)
+  aSpec.Trim(" \n\r\t,");
   
   // Count the commas 
   PRInt32 commaX = aSpec.FindChar(COMMA);
diff --git a/mozilla/layout/html/document/src/nsFrameSetFrame.cpp b/mozilla/layout/html/document/src/nsFrameSetFrame.cpp
index c23f4736ee4..eddaefe3e9b 100644
--- a/mozilla/layout/html/document/src/nsFrameSetFrame.cpp
+++ b/mozilla/layout/html/document/src/nsFrameSetFrame.cpp
@@ -693,7 +693,9 @@ nsHTMLFramesetFrame::ParseRowColSpec(nsString&       aSpec,
   static const PRUnichar PERCENT('%');
   static const PRUnichar COMMA(',');
 
-  aSpec.Trim(" \n\r\t"); // remove leading and trailing whitespace  
+  // remove leading and trailing whitespace
+  // also remove leading/trialing commas (bug 31482)
+  aSpec.Trim(" \n\r\t,");
   
   // Count the commas 
   PRInt32 commaX = aSpec.FindChar(COMMA);