diff --git a/src/core/game/PlayerImpl.ts b/src/core/game/PlayerImpl.ts
index d9ba8ba7c..75a3afcf9 100644
--- a/src/core/game/PlayerImpl.ts
+++ b/src/core/game/PlayerImpl.ts
@@ -390,6 +390,13 @@ export class PlayerImpl implements Player {
     if (other === this) {
       return false;
     }
+    if (this.isDisconnected() || other.isDisconnected()) {
+      // Disconnected players are marked as not-friendly even if they are allies,
+      // so we need to return early if either player is disconnected.
+      // Otherise we could end up sending an alliance request to someone
+      // we are already allied with.
+      return false;
+    }
     if (this.isFriendly(other) || !this.isAlive()) {
       return false;
     }