diff --git a/data.py b/data.py
index 5f7e171..eb06557 100644
--- a/data.py
+++ b/data.py
@@ -60,10 +60,12 @@ TABLES = [
     create table populations (
         id INTEGER PRIMARY KEY AUTOINCREMENT,
         species TEXT,
+        home_star INTEGER,
         pop INTEGER,
         planet INTEGER,
         vessel INTEGER,
         station INTEGER,
+        FOREIGN KEY(home_star) REFERENCES stars(id),
         FOREIGN KEY(planet) REFERENCES planets(id)
         check (
             ( case when planet  is null then 0 else 1 end
diff --git a/game.sqlite b/game.sqlite
index baf6bb0..f2d42c8 100644
Binary files a/game.sqlite and b/game.sqlite differ
diff --git a/population.py b/population.py
index 391a95f..dfe3ac0 100644
--- a/population.py
+++ b/population.py
@@ -31,7 +31,7 @@ def init_db(conn):
     c = conn.cursor()
     c.execute(
         '''\
-        select id, bio, industrial_capacity
+        select id, bio, industrial_capacity, star
         from planets
         where bio > 10000 and industrial_capacity > 10000
         '''
@@ -40,7 +40,7 @@ def init_db(conn):
 
     # Select some and set initial population and industry.
     home_worlds = sample(list(c.fetchall()), INITIAL_NUMBER_OF_SENTIENT_PEOPLES)
-    for planet_id, bio, industrial_capacity in home_worlds:
+    for planet_id, bio, industrial_capacity, home_star_id in home_worlds:
         bio -= INITIAL_POP  # We know bio is above 10000 from the query above.
         ind = min(INITIAL_POP, industrial_capacity)
         people_name = get_name_of_planets_star(c, planet_id) + 'ians'
@@ -49,8 +49,8 @@ def init_db(conn):
             (bio, ind, planet_id),
         )
         c.execute(
-            'insert into populations(species, pop, planet) values (?, ?, ?)',
-            (people_name, INITIAL_POP, planet_id),
+            'insert into populations(species, home_star, pop, planet) values (?, ?, ?, ?)',
+            (people_name, home_star_id, INITIAL_POP, planet_id),
         )
         # print(planet_id, bio, industrial_capacity)
     c.close()
diff --git a/server.py b/server.py
index 32ed776..0eb6990 100644
--- a/server.py
+++ b/server.py
@@ -74,16 +74,16 @@ def population_grows(db_cursor):
         select populations.id, populations.pop, planets.id, planets.bio
         from populations join planets
         on populations.planet = planets.id
+        and populations.home_star = planets.star
         '''
     )
-    # and populations.home_star = planets.star
     # People are only legally allowed to reproduce in their home
     # stellar systems.
     pops = list(db_cursor.fetchall())
     for pop_id, pop, planet_id, bio in pops:
         if pop > bio:
             # famine and death!  Woe!
-            print('WARNING population crash on planet {planet_id}!')
+            print(f'WARNING population crash on planet {planet_id}!')
             pop = bio >> 1
             bio //= 10
         else: