diff --git a/nml/actions/action5.py b/nml/actions/action5.py
index 461c1408..fb6a0a1f 100644
--- a/nml/actions/action5.py
+++ b/nml/actions/action5.py
@@ -78,7 +78,7 @@ class Action5BlockType:
     "AQUEDUCTS": (0x12, 8, Action5BlockType.OFFSET),
     "AUTORAIL": (0x13, 55, Action5BlockType.OFFSET),
     "FLAGS": (0x14, 36, Action5BlockType.OFFSET),
-    "OTTD_GUI": (0x15, 186, Action5BlockType.OFFSET),
+    "OTTD_GUI": (0x15, 191, Action5BlockType.OFFSET),
     "AIRPORT_PREVIEW": (0x16, 9, Action5BlockType.OFFSET),
     "RAILTYPE_TUNNELS": (0x17, 16, Action5BlockType.OFFSET),
     "OTTD_RECOLOUR": (0x18, 1, Action5BlockType.OFFSET),