diff --git a/src/tinyweb/db.py b/src/tinyweb/db.py
index 9c138a1..174bc7c 100644
--- a/src/tinyweb/db.py
+++ b/src/tinyweb/db.py
@@ -142,7 +142,7 @@ def _ensure_columns(db, table, columns):
     existing = {r[1] for r in db.execute(f"PRAGMA table_info({table})").fetchall()}
     for name, col_def in columns.items():
         if name not in existing:
-            db.execute(f"ALTER TABLE {table} ADD COLUMN {col_def}")
+            db.execute(f"ALTER TABLE {table} ADD COLUMN {name} {col_def}")
 
 
 def init_db():