Index: programs/winhelp/hlpfile.c
===================================================================
RCS file: /home/wine/wine/programs/winhelp/hlpfile.c,v
retrieving revision 1.29
diff -u -p -r1.29 hlpfile.c
--- programs/winhelp/hlpfile.c	23 May 2006 12:49:31 -0000	1.29
+++ programs/winhelp/hlpfile.c	10 Aug 2006 10:05:47 -0000
@@ -1498,8 +1498,17 @@ static BYTE *HLPFILE_UncompressLZ77(BYTE
                 int code   = GET_USHORT(ptr, 0);
                 int len    = 3 + (code >> 12);
                 int offset = code & 0xfff;
-                memcpy(newptr, newptr - offset - 1, len);
-                newptr += len;
+                /*
+                 * We must copy byte-by-byte here. We cannot use memcpy here -
+                 * areas are overlaps, so it's behaviour is unpredictable
+                 * (memcpy DOES NOT copy byte-by-byte because of some
+                 * optimizations).
+                 * bcopy also fails, it behaves like memmove, non memcpy.
+                 *
+                 * WINE versions of memcpy/memmove cannot be used by the
+                 * same reasons.
+                 */
+                for (; len>0; len--, newptr++) *newptr = *(newptr-offset-1);
                 ptr    += 2;
 	    }
             else *newptr++ = *ptr++;