diff --git a/src/openttd.h b/src/openttd.h
index e19dd22d64..6d6c670eb1 100644
--- a/src/openttd.h
+++ b/src/openttd.h
@@ -20,7 +20,6 @@ typedef EngineID *EngineList; ///< engine list type placeholder acceptable for C
 
 /* IDs used in Pools */
 typedef uint16 WaypointID;
-typedef uint16 SignID;
 typedef uint16 EngineRenewID;
 
 enum GameModes {
diff --git a/src/signs.h b/src/signs.h
index 3f014c0cc1..ebf32f2435 100644
--- a/src/signs.h
+++ b/src/signs.h
@@ -7,6 +7,7 @@
 
 #include "oldpool.h"
 
+typedef uint16 SignID;
 struct Sign;
 DECLARE_OLD_POOL(Sign, Sign, 2, 16000)