Cast void* to char* for pointer arithmetic.

diff --git a/files/smb.c b/files/smb.c
index e1eb44b..3fdb7d9 100644
--- a/files/smb.c
+++ b/files/smb.c
@@ -1111,7 +1111,7 @@
         if(!read)
             break;
         total += read;
-        buffer += read;
+        buffer = (char*)buffer + read;
         offset += read;
         if(total>=bytesToRead)
             break;