diff --git a/core/schema.rs b/core/schema.rs
index 20ae6380e..2d7c2f8d9 100644
--- a/core/schema.rs
+++ b/core/schema.rs
@@ -1033,6 +1033,9 @@ impl BTreeTable {
                 sql.push(' ');
                 sql.push_str(&column.ty_str);
             }
+            if column.notnull {
+                sql.push_str(" NOT NULL");
+            }
 
             if column.unique {
                 sql.push_str(" UNIQUE");
diff --git a/testing/alter_table.test b/testing/alter_table.test
index 172802395..5a856eca9 100755
--- a/testing/alter_table.test
+++ b/testing/alter_table.test
@@ -204,3 +204,10 @@ do_execsql_test_on_specific_db {:memory:} alter-table-rename-to-quoted-identifie
     "CREATE INDEX idx ON \"t t\" (\"b b\")"
     "2"
 }
+
+# https://github.com/tursodatabase/turso/issues/3391
+do_execsql_test_on_specific_db {:memory:} alter-table-add-notnull-col {
+    CREATE TABLE t (a);
+	ALTER TABLE t ADD b NOT NULL;
+	SELECT sql FROM sqlite_schema WHERE type = 'table' AND name = 't';
+} {{CREATE TABLE t (a, b NOT NULL)}}