diff --git a/src/nsCharSetProber.cpp b/src/nsCharSetProber.cpp
index 0429dd1..79d5ace 100644
--- a/src/nsCharSetProber.cpp
+++ b/src/nsCharSetProber.cpp
@@ -74,7 +74,7 @@ PRBool nsCharSetProber::FilterWithoutEnglishLetters(const char* aBuf, PRUint32 a
   if (meetMSB && curPtr > prevPtr) 
     while (prevPtr < curPtr) *newptr++ = *prevPtr++;  
 
-  newLen = newptr - *newBuf;
+  newLen = (PRUint32) (newptr - *newBuf);
 
   return PR_TRUE;
 }
@@ -119,7 +119,7 @@ PRBool nsCharSetProber::FilterWithEnglishLetters(const char* aBuf, PRUint32 aLen
     while (prevPtr < curPtr)
       *newptr++ = *prevPtr++;  
 
-  newLen = newptr - *newBuf;
+  newLen = (PRUint32) (newptr - *newBuf);
 
   return PR_TRUE;
 }