diff --git a/lib/Qpsmtpd/DB/File/DBM.pm b/lib/Qpsmtpd/DB/File/DBM.pm
index c038618..6126a1d 100644
--- a/lib/Qpsmtpd/DB/File/DBM.pm
+++ b/lib/Qpsmtpd/DB/File/DBM.pm
@@ -201,6 +201,7 @@ sub validate_dir {
     my ( $self, $d ) = @_;
     return 0 if ! $d;
     return 0 if ! -d $d;
+    return 0 if ! -w $d;
     return 1;
 }
 
diff --git a/t/qpsmtpd-db-file-dbm.t b/t/qpsmtpd-db-file-dbm.t
index 58a94a7..c9e471d 100644
--- a/t/qpsmtpd-db-file-dbm.t
+++ b/t/qpsmtpd-db-file-dbm.t
@@ -125,6 +125,13 @@ sub __validate_dir {
         'validate_dir(): false for non-existent directory' );
     is( $db->validate_dir('t/tmp'), 1,
         'validate_dir(): true for real directory' );
+    mkdir 't/tmp/wtest', 0555;
+    is( $db->validate_dir('t/tmp/wtest'), 0,
+        'validate_dir(): false for non-writeable directory' );
+    chmod 0777, 't/tmp/wtest';
+    is( $db->validate_dir('t/tmp/wtest'), 1,
+        'validate_dir(): true for writeable directory' );
+    rmdir 't/tmp/wtest';
 }
 
 sub __dir {