diff --git a/server/file.c b/server/file.c
index 60f50f4ba51..4ae1f7d05d5 100644
--- a/server/file.c
+++ b/server/file.c
@@ -73,7 +73,7 @@ static const struct object_ops file_ops =
 static int get_name_hash( const char *name )
 {
     int hash = 0;
-    while (*name) hash ^= *name++;
+    while (*name) hash ^= (unsigned char)*name++;
     return hash % NAME_HASH_SIZE;
 }