diff --git a/src/core/configuration/Config.ts b/src/core/configuration/Config.ts
index a67396205..971e8b1ad 100644
--- a/src/core/configuration/Config.ts
+++ b/src/core/configuration/Config.ts
@@ -135,6 +135,7 @@ export interface Config {
   deleteUnitCooldown(): Tick;
   defaultDonationAmount(sender: Player): number;
   unitInfo(type: UnitType): UnitInfo;
+  tradeShipShortRangeDebuff(): number;
   tradeShipGold(dist: number, numPorts: number): Gold;
   tradeShipSpawnRate(
     numTradeShips: number,
diff --git a/src/core/configuration/DefaultConfig.ts b/src/core/configuration/DefaultConfig.ts
index a9e9c01a7..3aca8e369 100644
--- a/src/core/configuration/DefaultConfig.ts
+++ b/src/core/configuration/DefaultConfig.ts
@@ -371,9 +371,10 @@ export class DefaultConfig implements Config {
   }
 
   tradeShipGold(dist: number, numPorts: number): Gold {
-    // Sigmoid: concave start, sharp S-curve middle, linear end - heavily punishes trades under 200
+    // Sigmoid: concave start, sharp S-curve middle, linear end - heavily punishes trades under range debuff.
+    const debuff = this.tradeShipShortRangeDebuff();
     const baseGold =
-      100_000 / (1 + Math.exp(-0.03 * (dist - 200))) + 100 * dist;
+      100_000 / (1 + Math.exp(-0.03 * (dist - debuff))) + 100 * dist;
     const numPortBonus = numPorts - 1;
     // Hyperbolic decay, midpoint at 5 ports, 3x bonus max.
     const bonus = 1 + 2 * (numPortBonus / (numPortBonus + 5));
@@ -777,6 +778,10 @@ export class DefaultConfig implements Config {
     return 20;
   }
 
+  tradeShipShortRangeDebuff(): number {
+    return 200;
+  }
+
   proximityBonusPortsNb(totalPorts: number) {
     return within(totalPorts / 3, 4, totalPorts);
   }
diff --git a/src/core/execution/PortExecution.ts b/src/core/execution/PortExecution.ts
index cdc16a496..de7b70752 100644
--- a/src/core/execution/PortExecution.ts
+++ b/src/core/execution/PortExecution.ts
@@ -58,7 +58,7 @@ export class PortExecution implements Execution {
       return;
     }
 
-    const ports = this.player.tradingPorts(this.port);
+    const ports = this.tradingPorts();
 
     if (ports.length === 0) {
       return;
@@ -103,4 +103,40 @@ export class PortExecution implements Execution {
       }
     }
   }
+
+  // It's a probability list, so if an element appears twice it's because it's
+  // twice more likely to be picked later.
+  tradingPorts(): Unit[] {
+    const ports = this.mg
+      .players()
+      .filter((p) => p !== this.port!.owner() && p.canTrade(this.port!.owner()))
+      .flatMap((p) => p.units(UnitType.Port))
+      .sort((p1, p2) => {
+        return (
+          this.mg.manhattanDist(this.port!.tile(), p1.tile()) -
+          this.mg.manhattanDist(this.port!.tile(), p2.tile())
+        );
+      });
+
+    const weightedPorts: Unit[] = [];
+
+    for (const [i, otherPort] of ports.entries()) {
+      const expanded = new Array(otherPort.level()).fill(otherPort);
+      weightedPorts.push(...expanded);
+      const tooClose =
+        this.mg.manhattanDist(this.port!.tile(), otherPort.tile()) <
+        this.mg.config().tradeShipShortRangeDebuff();
+      const closeBonus =
+        i < this.mg.config().proximityBonusPortsNb(ports.length);
+      if (!tooClose && closeBonus) {
+        // If the port is close, but not too close, add it again
+        // to increase the chances of trading with it.
+        weightedPorts.push(...expanded);
+      }
+      if (!tooClose && this.port!.owner().isFriendly(otherPort.owner())) {
+        weightedPorts.push(...expanded);
+      }
+    }
+    return weightedPorts;
+  }
 }
diff --git a/src/core/game/Game.ts b/src/core/game/Game.ts
index bd7a184f6..061143d55 100644
--- a/src/core/game/Game.ts
+++ b/src/core/game/Game.ts
@@ -648,7 +648,6 @@ export interface Player {
   // Misc
   toUpdate(): PlayerUpdate;
   playerProfile(): PlayerProfile;
-  tradingPorts(port: Unit): Unit[];
   // WARNING: this operation is expensive.
   bestTransportShipSpawn(tile: TileRef): TileRef | false;
 }
diff --git a/src/core/game/PlayerImpl.ts b/src/core/game/PlayerImpl.ts
index 955eb1474..2ebd85aba 100644
--- a/src/core/game/PlayerImpl.ts
+++ b/src/core/game/PlayerImpl.ts
@@ -1214,34 +1214,4 @@ export class PlayerImpl implements Player {
   bestTransportShipSpawn(targetTile: TileRef): TileRef | false {
     return bestShoreDeploymentSource(this.mg, this, targetTile);
   }
-
-  // It's a probability list, so if an element appears twice it's because it's
-  // twice more likely to be picked later.
-  tradingPorts(port: Unit): Unit[] {
-    const ports = this.mg
-      .players()
-      .filter((p) => p !== port.owner() && p.canTrade(port.owner()))
-      .flatMap((p) => p.units(UnitType.Port))
-      .sort((p1, p2) => {
-        return (
-          this.mg.manhattanDist(port.tile(), p1.tile()) -
-          this.mg.manhattanDist(port.tile(), p2.tile())
-        );
-      });
-
-    const weightedPorts: Unit[] = [];
-
-    for (const [i, otherPort] of ports.entries()) {
-      const expanded = new Array(otherPort.level()).fill(otherPort);
-      weightedPorts.push(...expanded);
-      if (i < this.mg.config().proximityBonusPortsNb(ports.length)) {
-        weightedPorts.push(...expanded);
-      }
-      if (port.owner().isFriendly(otherPort.owner())) {
-        weightedPorts.push(...expanded);
-      }
-    }
-
-    return weightedPorts;
-  }
 }
diff --git a/tests/PlayerImpl.test.ts b/tests/PlayerImpl.test.ts
index 7f47a1cd2..71d022f22 100644
--- a/tests/PlayerImpl.test.ts
+++ b/tests/PlayerImpl.test.ts
@@ -83,22 +83,6 @@ describe("PlayerImpl", () => {
     expect(cityToUpgrade).toBe(false);
   });
 
-  test("Destination ports chances scale with level", () => {
-    game.config().proximityBonusPortsNb = () => 0;
-
-    player.conquer(game.ref(10, 10));
-    const playerPort = player.buildUnit(UnitType.Port, game.ref(10, 10), {});
-
-    other.conquer(game.ref(0, 0));
-    const otherPort = other.buildUnit(UnitType.Port, game.ref(0, 0), {});
-    otherPort.increaseLevel();
-    otherPort.increaseLevel();
-
-    const ports = player.tradingPorts(playerPort);
-
-    expect(ports.length).toBe(3);
-  });
-
   test("Can't send alliance requests when dead", () => {
     // conquer other
     const otherTiles = other.tiles();
diff --git a/tests/PortExecution.test.ts b/tests/PortExecution.test.ts
new file mode 100644
index 000000000..d38500315
--- /dev/null
+++ b/tests/PortExecution.test.ts
@@ -0,0 +1,92 @@
+import { PortExecution } from "../src/core/execution/PortExecution";
+import {
+  Game,
+  Player,
+  PlayerInfo,
+  PlayerType,
+  UnitType,
+} from "../src/core/game/Game";
+import { setup } from "./util/Setup";
+
+let game: Game;
+let player: Player;
+let other: Player;
+
+describe("PortExecution", () => {
+  beforeEach(async () => {
+    game = await setup(
+      "half_land_half_ocean",
+      {
+        instantBuild: true,
+      },
+      [
+        new PlayerInfo("player", PlayerType.Human, null, "player_id"),
+        new PlayerInfo("other", PlayerType.Human, null, "other_id"),
+      ],
+    );
+
+    while (game.inSpawnPhase()) {
+      game.executeNextTick();
+    }
+
+    player = game.player("player_id");
+    player.addGold(BigInt(1000000));
+    other = game.player("other_id");
+
+    game.config().structureMinDist = () => 10;
+  });
+
+  test("Destination ports chances scale with level", () => {
+    game.config().proximityBonusPortsNb = () => 0;
+    game.config().tradeShipShortRangeDebuff = () => 0;
+
+    player.conquer(game.ref(7, 10));
+    const execution = new PortExecution(player, game.ref(7, 10));
+    execution.init(game, 0);
+    execution.tick(0);
+
+    other.conquer(game.ref(0, 0));
+    const otherPort = other.buildUnit(UnitType.Port, game.ref(0, 0), {});
+    otherPort.increaseLevel();
+    otherPort.increaseLevel();
+
+    const ports = execution.tradingPorts();
+
+    expect(ports.length).toBe(3);
+  });
+
+  test("Trade ship proximity bonus", () => {
+    game.config().proximityBonusPortsNb = () => 10;
+    game.config().tradeShipShortRangeDebuff = () => 0;
+
+    player.conquer(game.ref(7, 10));
+    const execution = new PortExecution(player, game.ref(7, 10));
+    execution.init(game, 0);
+    execution.tick(0);
+
+    other.conquer(game.ref(0, 0));
+    other.buildUnit(UnitType.Port, game.ref(0, 0), {});
+
+    const ports = execution.tradingPorts();
+
+    expect(ports.length).toBe(2);
+  });
+
+  test("Trade ship short range debuff", () => {
+    game.config().proximityBonusPortsNb = () => 10;
+    // Short range debuff cancels out the proximity bonus.
+    game.config().tradeShipShortRangeDebuff = () => 100;
+
+    player.conquer(game.ref(7, 10));
+    const execution = new PortExecution(player, game.ref(7, 10));
+    execution.init(game, 0);
+    execution.tick(0);
+
+    other.conquer(game.ref(0, 0));
+    other.buildUnit(UnitType.Port, game.ref(0, 0), {});
+
+    const ports = execution.tradingPorts();
+
+    expect(ports.length).toBe(1);
+  });
+});