diff --git a/database.py b/database.py
index b6a93e3..13db531 100644
--- a/database.py
+++ b/database.py
@@ -190,6 +190,7 @@ def update_task(task_id, **kwargs):
 def delete_task(task_id):
     conn = get_connection()
     try:
+        conn.execute('UPDATE goals SET "selected_task_id" = NULL WHERE "selected_task_id" = ?', (task_id,))
         conn.execute("DELETE FROM tasks WHERE id = ?", (task_id,))
         conn.commit()
     finally:
diff --git a/schema.py b/schema.py
index a9e1f02..53c092c 100644
--- a/schema.py
+++ b/schema.py
@@ -22,7 +22,7 @@ CREATE TABLE IF NOT EXISTS goals (
     activated INTEGER NOT NULL DEFAULT 1,
     selected_task_id INTEGER,
     FOREIGN KEY (user_id) REFERENCES users(id),
-    FOREIGN KEY (selected_task_id) REFERENCES tasks(id)
+    FOREIGN KEY (selected_task_id) REFERENCES tasks(id) ON DELETE SET NULL
 )
 """