diff --git a/engine.c b/engine.c
--- a/engine.c
+++ b/engine.c
@@ -887,7 +887,7 @@ int32 CmdRenameEngine(int x, int y, uint
 {
 	StringID str;
 
-	if (!IsEngineIndex(p1)) return CMD_ERROR;
+	if (!IsEngineIndex(p1) || _cmd_text[0] == '\0') return CMD_ERROR;
 
 	str = AllocateNameUnique(_cmd_text, 0);
 	if (str == 0) return CMD_ERROR;
diff --git a/misc_cmd.c b/misc_cmd.c
--- a/misc_cmd.c
+++ b/misc_cmd.c
@@ -129,6 +129,8 @@ int32 CmdChangeCompanyName(int x, int y,
 	StringID str;
 	Player *p;
 
+	if (_cmd_text[0] == '\0') return CMD_ERROR;
+
 	str = AllocateNameUnique(_cmd_text, 4);
 	if (str == 0) return CMD_ERROR;
 
@@ -153,6 +155,8 @@ int32 CmdChangePresidentName(int x, int 
 	StringID str;
 	Player *p;
 
+	if (_cmd_text[0] == '\0') return CMD_ERROR;
+
 	str = AllocateNameUnique(_cmd_text, 4);
 	if (str == 0) return CMD_ERROR;
 
diff --git a/station_cmd.c b/station_cmd.c
--- a/station_cmd.c
+++ b/station_cmd.c
@@ -2653,7 +2653,7 @@ int32 CmdRenameStation(int x, int y, uin
 	StringID str,old_str;
 	Station *st;
 
-	if (!IsStationIndex(p1)) return CMD_ERROR;
+	if (!IsStationIndex(p1) || _cmd_text[0] == '\0') return CMD_ERROR;
 	st = GetStation(p1);
 
 	if (!IsValidStation(st) || !CheckOwnership(st->owner)) return CMD_ERROR;
diff --git a/town_cmd.c b/town_cmd.c
--- a/town_cmd.c
+++ b/town_cmd.c
@@ -1447,7 +1447,7 @@ int32 CmdRenameTown(int x, int y, uint32
 	StringID str;
 	Town *t;
 
-	if (!IsTownIndex(p1)) return CMD_ERROR;
+	if (!IsTownIndex(p1) || _cmd_text[0] == '\0') return CMD_ERROR;
 
 	t = GetTown(p1);
 
diff --git a/vehicle.c b/vehicle.c
--- a/vehicle.c
+++ b/vehicle.c
@@ -1654,7 +1654,7 @@ int32 CmdNameVehicle(int x, int y, uint3
 	Vehicle *v;
 	StringID str;
 
-	if (!IsVehicleIndex(p1)) return CMD_ERROR;
+	if (!IsVehicleIndex(p1) || _cmd_text[0] == '\0') return CMD_ERROR;
 
 	v = GetVehicle(p1);