diff --git a/src/company_cmd.cpp b/src/company_cmd.cpp
--- a/src/company_cmd.cpp
+++ b/src/company_cmd.cpp
@@ -89,6 +89,9 @@ void SetLocalCompany(CompanyID new_compa
 	/* company could also be COMPANY_SPECTATOR or OWNER_NONE */
 	assert(Company::IsValidID(new_company) || new_company == COMPANY_SPECTATOR || new_company == OWNER_NONE);
 
+	/* Delete the chat window, if you were team chatting. */
+	InvalidateWindowData(WC_SEND_NETWORK_MSG, DESTTYPE_TEAM, _local_company);
+
 	_local_company = new_company;
 
 	/* Delete any construction windows... */