diff --git a/intl/uconv/ucvlatin/Makefile.in b/intl/uconv/ucvlatin/Makefile.in
index 3e7a3683622b..62761318a4b6 100644
--- a/intl/uconv/ucvlatin/Makefile.in
+++ b/intl/uconv/ucvlatin/Makefile.in
@@ -48,6 +48,7 @@ FORCE_STATIC_LIB = 1
 LIBXUL_LIBRARY = 1
 
 REQUIRES	= xpcom \
+		  string \
 		  uconv \
 		  $(NULL)
 
diff --git a/intl/uconv/ucvlatin/nsUTF32ToUnicode.cpp b/intl/uconv/ucvlatin/nsUTF32ToUnicode.cpp
index 03304e5b1a3e..e659205fdf72 100644
--- a/intl/uconv/ucvlatin/nsUTF32ToUnicode.cpp
+++ b/intl/uconv/ucvlatin/nsUTF32ToUnicode.cpp
@@ -40,6 +40,7 @@
 
 #include "nsUCSupport.h"
 #include "nsUTF32ToUnicode.h"
+#include "nsCharTraits.h"
 #include <string.h>
 
 //----------------------------------------------------------------------
@@ -96,9 +97,7 @@ static nsresult ConvertCommon(const char * aSrc,
     ucs4 =  aIsLE ? LE_STRING_TO_UCS4(aBuffer) : BE_STRING_TO_UCS4(aBuffer); 
     if (ucs4 < 0x10000L)  // BMP
     {
-      // XXX Do we have to convert surrogate code points to the replacement
-      // character (0xfffd)?  
-      *dest++= PRUnichar(ucs4);
+      *dest++= IS_SURROGATE(ucs4) ? UCS2_REPLACEMENT_CHAR : PRUnichar(ucs4);
     }
     else if (ucs4 < 0x110000L)  // plane 1 through plane 16 
     {
@@ -108,9 +107,8 @@ static nsresult ConvertCommon(const char * aSrc,
         *aDestLength = 0;
         return NS_OK_UDEC_MOREOUTPUT;
       }
-      // ((ucs4 - 0x10000) >> 10) + 0xd800;
-      *dest++= PRUnichar((ucs4 >> 10) + 0xd7c0);  // high surrogate
-      *dest++= PRUnichar(ucs4 & 0x3ffL | 0xdc00); // low surrogate
+      *dest++= H_SURROGATE(ucs4);
+      *dest++= L_SURROGATE(ucs4);
     }       
     // Codepoints in plane 17 and higher (> 0x10ffff)
     // are not representable in UTF-16 we use for the internal
@@ -119,7 +117,7 @@ static nsresult ConvertCommon(const char * aSrc,
     // in plane 17 and higher. Therefore, we convert them
     // to Unicode replacement character (0xfffd).
     else                   
-      *dest++ = 0xfffd;
+      *dest++ = UCS2_REPLACEMENT_CHAR;
     src += *aState;
     *aState = 0;
   }
@@ -141,20 +139,18 @@ static nsresult ConvertCommon(const char * aSrc,
     ucs4 =  aIsLE ? LE_STRING_TO_UCS4(src) : BE_STRING_TO_UCS4(src); 
     if (ucs4 < 0x10000L)  // BMP
     {
-      // XXX Do we have to convert surrogate code points to the replacement
-      // character (0xfffd)?  
-      *dest++= PRUnichar(ucs4);
+      *dest++= IS_SURROGATE(ucs4) ? UCS2_REPLACEMENT_CHAR : PRUnichar(ucs4);
     }
     else if (ucs4 < 0x110000L)  // plane 1 through plane 16 
     {
       if (destEnd - dest < 2) 
         break;
       // ((ucs4 - 0x10000) >> 10) + 0xd800;
-      *dest++= PRUnichar((ucs4 >> 10) + 0xd7c0); 
-      *dest++= PRUnichar(ucs4 & 0x3ffL | 0xdc00);
+      *dest++= H_SURROGATE(ucs4);
+      *dest++= L_SURROGATE(ucs4);
     }       
     else                       // plane 17 and higher
-      *dest++ = 0xfffd;
+      *dest++ = UCS2_REPLACEMENT_CHAR;
   }
 
   //output not finished, output buffer too short