diff --git a/agent.cc b/agent.cc
index 054db38..0677865 100644
--- a/agent.cc
+++ b/agent.cc
@@ -94,6 +94,8 @@ void
 agent::chenergy(int delta)
 {
 	energy += delta;
+	if (energy > world::max_energy)
+		energy = world::max_energy;
 	if (energy <= 0)
 		die();
 }
diff --git a/world.h b/world.h
index 4381044..47a3b81 100644
--- a/world.h
+++ b/world.h
@@ -4,6 +4,7 @@
 struct world {
 	const static int newborn_energy = 5000;
 	const static int herb_energy = 1000;
+	const static int max_energy = 20000;
 
 	const static int move_cost = -50;
 	const static int attack_cost = -400;