--- a/cdb.scm
+++ b/cdb.scm
@@ -60,7 +60,7 @@
   (unless (slot-bound? self 'path)
     (error "path must be set to open cdb database"))
   (when (cdb-file-of self)
-    (errorf "cdb ~S already opened" cdb))
+    (errorf "cdb ~s already opened" (cdb-file-of self)))
   (let ((path (slot-ref self 'path))
         (rwmode (slot-ref self 'rw-mode)))
     (case rwmode
--- a/cdb.stub
+++ b/cdb.stub
@@ -69,7 +69,7 @@
 
  static void cdb_finalize(ScmObj obj, void *data)
  {
-   ScmCdb *cdb = SCM_CDB(cdb);
+   ScmCdb *cdb = SCM_CDB(obj);
    switch (cdb->status) {
    case OPEN_QUERY:
      cdb_free(&cdb->cdb); close(cdb_fileno(&cdb->cdb));