diff --git a/asminc/tgi-kernel.inc b/asminc/tgi-kernel.inc
index a299d921a..32c47a5e6 100644
--- a/asminc/tgi-kernel.inc
+++ b/asminc/tgi-kernel.inc
@@ -71,6 +71,11 @@ TGI_HDR_OUTTEXT         = TGI_HDR_JUMPTAB+42    ; OUTTEXT routine
 
 TGI_HDR_JUMPCOUNT       = 21            ; Number of jump vectors
 
+;------------------------------------------------------------------------------
+; The TGI API version, stored at TGI_HDR_VERSION
+
+TGI_API_VERSION         = $01
+
 ;------------------------------------------------------------------------------
 ; Text style constants