diff --git a/lib/UnQLite.pm b/lib/UnQLite.pm
index 0fb5a71..9efb43b 100644
--- a/lib/UnQLite.pm
+++ b/lib/UnQLite.pm
@@ -185,14 +185,14 @@ UnQLite - Perl bindings for UnQLite
 
     use UnQLite;
 
-    my $db = UnQLite->open('foo.db');
+    my $db = UnQLite->open('foo.db', UNQLITE_OPEN_READWRITE|UNQLITE_OPEN_CREATE);
     $db->kv_store('foo', 'bar');
     say $db->kv_fetch('foo'); # => bar
     $db->kv_delete('foo');
     undef $db; # close database
 
     # tie interface
-    tie my %hash, 'UnQLite', 'foo.db';
+    tie my %hash, 'UnQLite', 'foo.db', UNQLITE_OPEN_READWRITE;
     $hash{foo} = 'bar';
     say $hash{foo}; # => bar
 
@@ -216,6 +216,17 @@ B<You can use UnQLite.pm as DBM>.
 
 Open the database.
 
+Modes:
+
+    UNQLITE_OPEN_CREATE      (Default)
+    UNQLITE_OPEN_READONLY
+    UNQLITE_OPEN_READWRITE
+    UNQLITE_OPEN_EXCLUSIVE
+    UNQLITE_OPEN_TEMP_DB
+    UNQLITE_OPEN_OMIT_JOURNALING
+    UNQLITE_OPEN_IN_MEMORY
+    UNQLITE_OPEN_MMAP
+
 =item C<< $db->kv_store($key, $value); >>
 
 Store the entry to database.
diff --git a/lib/UnQLite.xs b/lib/UnQLite.xs
index 8321be0..0e82615 100644
--- a/lib/UnQLite.xs
+++ b/lib/UnQLite.xs
@@ -42,34 +42,44 @@ PROTOTYPES: DISABLE
 
 BOOT:
     HV* stash = gv_stashpvn("UnQLite", strlen("UnQLite"), TRUE);
-    newCONSTSUB(stash, "UNQLITE_OK", newSViv(UNQLITE_OK));
-    newCONSTSUB(stash, "UNQLITE_NOMEM", newSViv(UNQLITE_NOMEM));
-    newCONSTSUB(stash, "UNQLITE_ABORT", newSViv(UNQLITE_ABORT));
-    newCONSTSUB(stash, "UNQLITE_IOERR", newSViv(UNQLITE_IOERR));
-    newCONSTSUB(stash, "UNQLITE_CORRUPT", newSViv(UNQLITE_CORRUPT));
-    newCONSTSUB(stash, "UNQLITE_LOCKED", newSViv(UNQLITE_LOCKED));
-    newCONSTSUB(stash, "UNQLITE_BUSY", newSViv(UNQLITE_BUSY));
-    newCONSTSUB(stash, "UNQLITE_DONE", newSViv(UNQLITE_DONE));
-    newCONSTSUB(stash, "UNQLITE_PERM", newSViv(UNQLITE_PERM));
-    newCONSTSUB(stash, "UNQLITE_NOTIMPLEMENTED", newSViv(UNQLITE_NOTIMPLEMENTED));
-    newCONSTSUB(stash, "UNQLITE_NOTFOUND", newSViv(UNQLITE_NOTFOUND));
-    newCONSTSUB(stash, "UNQLITE_NOOP", newSViv(UNQLITE_NOOP));
-    newCONSTSUB(stash, "UNQLITE_INVALID", newSViv(UNQLITE_INVALID));
-    newCONSTSUB(stash, "UNQLITE_EOF", newSViv(UNQLITE_EOF));
-    newCONSTSUB(stash, "UNQLITE_UNKNOWN", newSViv(UNQLITE_UNKNOWN));
-    newCONSTSUB(stash, "UNQLITE_LIMIT", newSViv(UNQLITE_LIMIT));
-    newCONSTSUB(stash, "UNQLITE_EXISTS", newSViv(UNQLITE_EXISTS));
-    newCONSTSUB(stash, "UNQLITE_EMPTY", newSViv(UNQLITE_EMPTY));
-    newCONSTSUB(stash, "UNQLITE_COMPILE_ERR", newSViv(UNQLITE_COMPILE_ERR));
-    newCONSTSUB(stash, "UNQLITE_VM_ERR", newSViv(UNQLITE_VM_ERR));
-    newCONSTSUB(stash, "UNQLITE_FULL", newSViv(UNQLITE_FULL));
-    newCONSTSUB(stash, "UNQLITE_CANTOPEN", newSViv(UNQLITE_CANTOPEN));
-    newCONSTSUB(stash, "UNQLITE_READ_ONLY", newSViv(UNQLITE_READ_ONLY));
-    newCONSTSUB(stash, "UNQLITE_LOCKERR", newSViv(UNQLITE_LOCKERR));
-
-    newCONSTSUB(stash, "UNQLITE_CURSOR_MATCH_EXACT", newSViv(UNQLITE_CURSOR_MATCH_EXACT));
-    newCONSTSUB(stash, "UNQLITE_CURSOR_MATCH_LE", newSViv(UNQLITE_CURSOR_MATCH_LE));
-    newCONSTSUB(stash, "UNQLITE_CURSOR_MATCH_GE", newSViv(UNQLITE_CURSOR_MATCH_GE));
+#define _XSTR(s) _STR(s)
+#define _STR(s)  #s
+#define UnConst(c) newCONSTSUB(stash, "UNQ"_XSTR(c), newSViv(UNQ##c))
+    UnConst(LITE_OK);
+    UnConst(LITE_NOMEM);
+    UnConst(LITE_ABORT);
+    UnConst(LITE_IOERR);
+    UnConst(LITE_CORRUPT);
+    UnConst(LITE_LOCKED);
+    UnConst(LITE_BUSY);
+    UnConst(LITE_DONE);
+    UnConst(LITE_PERM);
+    UnConst(LITE_NOTIMPLEMENTED);
+    UnConst(LITE_NOTFOUND);
+    UnConst(LITE_NOOP);
+    UnConst(LITE_INVALID);
+    UnConst(LITE_EOF);
+    UnConst(LITE_UNKNOWN);
+    UnConst(LITE_LIMIT);
+    UnConst(LITE_EXISTS);
+    UnConst(LITE_EMPTY);
+    UnConst(LITE_COMPILE_ERR);
+    UnConst(LITE_VM_ERR);
+    UnConst(LITE_FULL);
+    UnConst(LITE_CANTOPEN);
+    UnConst(LITE_READ_ONLY);
+    UnConst(LITE_LOCKERR);
+    UnConst(LITE_OPEN_READONLY);
+    UnConst(LITE_OPEN_READWRITE);
+    UnConst(LITE_OPEN_CREATE);
+    UnConst(LITE_OPEN_EXCLUSIVE);
+    UnConst(LITE_OPEN_TEMP_DB);
+    UnConst(LITE_OPEN_OMIT_JOURNALING);
+    UnConst(LITE_OPEN_IN_MEMORY);
+    UnConst(LITE_OPEN_MMAP);
+    UnConst(LITE_CURSOR_MATCH_EXACT);
+    UnConst(LITE_CURSOR_MATCH_LE);
+    UnConst(LITE_CURSOR_MATCH_GE);
 
 SV*
 open(klass, filename, mode=UNQLITE_OPEN_CREATE)