diff --git a/src/imdb-query.c b/src/imdb-query.c
index 50f564d..8717e68 100644
--- a/src/imdb-query.c
+++ b/src/imdb-query.c
@@ -179,13 +179,12 @@ int main(int argc, char **argv)
   const char *db_path = NULL;
   float maxdiff = 0.10;
   unsigned short int cols = 64, map = 0, ret = 0;
-  imdb_db_t db;
+  imdb_db_t *db = NULL;
   uint64_t a = 0, b = 0;
   char *c = NULL;
+  int err;
   char opt = '\0';
 
-  memset(&db, 0x0, sizeof(imdb_db_t));
-
   if (argc < 3)
     usage(EXIT_FAILURE);
 
@@ -243,8 +242,8 @@ int main(int argc, char **argv)
     exit(EXIT_FAILURE);
   }
 
-  if (imdb_open(&db, db_path, 0) == -1) {
-    fprintf(stderr, "database open: %s\n", db.error);
+  if ((db = imdb_open(db_path, 0, &err)) == NULL) {
+    fprintf(stderr, "database open: %d\n", err);
     exit(EXIT_FAILURE);
   }
 
@@ -254,34 +253,34 @@ int main(int argc, char **argv)
         fprintf(stderr, "can't parse number\n");
         usage(EXIT_FAILURE);
       }
-      ret = search_similar(&db, a, maxdiff);
+      ret = search_similar(db, a, maxdiff);
       break;
     case bitmap :
       if (a <= 0) {
         fprintf(stderr, "can't parse number\n");
         usage(EXIT_FAILURE);
       }
-      ret = rec_bitmap(&db, a);
+      ret = rec_bitmap(db, a);
       break;
     case usage_map :
-      ret = db_usage_map(&db, cols);
+      ret = db_usage_map(db, cols);
       break;
     case usage_slice :
-      ret = db_usage_slice(&db, a, b);
+      ret = db_usage_slice(db, a, b);
       break;
     case diff :
       if (a <= 0 || b <= 0) {
         fprintf(stderr, "both numbers must be set\n");
         exit(EXIT_FAILURE);
       }
-      ret = rec_diff(&db, a, b, map);
+      ret = rec_diff(db, a, b, map);
       break;
     default :
       usage(EXIT_SUCCESS);
       break;
   }
 
-  imdb_close(&db);
+  imdb_close(db);
 
   return ret;
 }
diff --git a/src/imdb-write.c b/src/imdb-write.c
index de1e217..9cfb911 100644
--- a/src/imdb-write.c
+++ b/src/imdb-write.c
@@ -25,10 +25,10 @@ int main(int argc, char **argv)
   const char *db_path = NULL;
   const char *sample = NULL;
   const char *c = NULL;
-  imdb_db_t  db;
+  imdb_db_t  *db = NULL;
   imdb_rec_t rec;
+  int err;
 
-  memset(&db,  0x0, sizeof(imdb_db_t));
   memset(&rec, 0x0, sizeof(imdb_rec_t));
 
   if (argc < 3)
@@ -67,8 +67,14 @@ int main(int argc, char **argv)
     usage(EXIT_FAILURE);
   }
 
-  if (mode != init && imdb_open(&db, db_path, 1) != 0) {
-    fprintf(stderr, "can't open database: %s\n", db.error);
+  if (mode == init) {
+    if (!imdb_create(db_path)) {
+      fprintf(stderr, "database init: %s\n", strerror(errno));
+      exit(EXIT_FAILURE);
+    }
+  }
+  if ((db = imdb_open(db_path, 1, &err)) == NULL) {
+    fprintf(stderr, "can't open database: %d\n", err);
     exit(EXIT_FAILURE);
   }
 
@@ -80,28 +86,25 @@ int main(int argc, char **argv)
         fprintf(stderr, "sampler failure\n");
         exit(EXIT_FAILURE);
       }
-      if (imdb_write_rec(&db, &rec) < 1) {
-        fprintf(stderr, "%s\n", db.error);
+      if (imdb_write_rec(db, &rec) < 1) {
+        fprintf(stderr, "%s\n", db->error);
         exit(EXIT_FAILURE);
       }
       break;
     case del :
-      if (imdb_write_rec(&db, &rec) < 1) {
-        fprintf(stderr, "%s\n", db.error);
+      if (imdb_write_rec(db, &rec) < 1) {
+        fprintf(stderr, "%s\n", db->error);
         exit(EXIT_FAILURE);
       }
       break;
     case init :
-      if (!imdb_create(db_path)) {
-        fprintf(stderr, "database init: %s\n", strerror(errno));
-        exit(EXIT_FAILURE);
-      }
+      /* this case already handled above */
       break;
     default:
       usage(EXIT_FAILURE);
       break;
   }
-  imdb_close(&db);
+  imdb_close(db);
 
   exit(EXIT_SUCCESS);
 }