diff --git a/dlls/mpr/pwcache.c b/dlls/mpr/pwcache.c
index 8e3c191..e12369d 100644
--- a/dlls/mpr/pwcache.c
+++ b/dlls/mpr/pwcache.c
@@ -282,7 +282,7 @@ UINT WINAPI WNetEnumCachedPasswords(
         /* decode the value */
         for(j=5; j<val_sz; j+=2 )
         {
-            CHAR hi = ctox( val[j] ), lo = ctox( val[j+1] );
+            signed char hi = ctox( val[j] ), lo = ctox( val[j+1] );
             if( ( hi < 0 ) || ( lo < 0 ) )
                 break;
             val[(j-5)/2] = (hi<<4) | lo;