diff --git a/sql/init.sql b/sql/init.sql
index 4311f08..b7fe1d2 100644
--- a/sql/init.sql
+++ b/sql/init.sql
@@ -4,7 +4,7 @@ CREATE TABLE elections (
     tokens INTEGER NOT NULL,
     is_anonymous INTEGER NOT NULL,
     max_voters INTEGER, -- mandatory when election is anonymous
-    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
     expires_at DATETIME NOT NULL,
     CHECK (is_anonymous = 0 OR (is_anonymous = 1 AND max_voters IS NOT NULL AND max_voters >= 1))
 );
@@ -55,10 +55,10 @@ END;
 CREATE TABLE votes (
     voter_identity TEXT NOT NULL,
     election_id INTEGER NOT NULL,
-    choice_text TEXT,
-    tokens INTEGER,
+    choice_text TEXT NOT NULL,
+    tokens INTEGER NOT NULL,
     calculated_vote_count GENERATED ALWAYS AS (floor(sqrt(tokens))) VIRTUAL,
-    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
     PRIMARY KEY (voter_identity, choice_text),
     FOREIGN KEY (voter_identity, election_id) REFERENCES voters (identity, election_id),
     FOREIGN KEY (choice_text, election_id) REFERENCES choices (text, election_id),