diff --git a/mozilla/intl/unicharutil/util/gensymmtable.pl b/mozilla/intl/unicharutil/util/gensymmtable.pl
index fca4edfe74e..63fdf0731e9 100644
--- a/mozilla/intl/unicharutil/util/gensymmtable.pl
+++ b/mozilla/intl/unicharutil/util/gensymmtable.pl
@@ -100,8 +100,8 @@ foreach $block (0 .. 0xff) {
 }
 
 # Generate conversion method
-print OUT "\nstatic PRUnichar Mirrored(PRUnichar u)\n{\n";
-print OUT "  switch (u & 0xFF00) {\n";
+print OUT "\nstatic PRUint32 Mirrored(PRUint32 u)\n{\n";
+print OUT "  switch (u & 0xFFFFFF00) {\n";
 print OUT "    // XOR the character with the bitmap in the conversion table to give the symmetric equivalent\n";
 foreach $block (0 .. 0xff) {
   if (1==@isblock[$block]) {
diff --git a/mozilla/intl/unicharutil/util/symmtable.h b/mozilla/intl/unicharutil/util/symmtable.h
index 36345898a58..31ad6ac7bbf 100644
--- a/mozilla/intl/unicharutil/util/symmtable.h
+++ b/mozilla/intl/unicharutil/util/symmtable.h
@@ -127,9 +127,9 @@ const static PRUint8 symmtable_30[256] = {
 /* F_ */    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0, 
 };
 
-static PRUnichar Mirrored(PRUnichar u)
+static PRUint32 Mirrored(PRUint32 u)
 {
-  switch (u & 0xFF00) {
+  switch (u & 0xFFFFFF00) {
     // XOR the character with the bitmap in the conversion table to give the symmetric equivalent
     case 0:
       u ^= symmtable_00[u & 0xff];