diff --git a/src/p_acs.h b/src/p_acs.h
index fb33a6504..f93773635 100644
--- a/src/p_acs.h
+++ b/src/p_acs.h
@@ -97,7 +97,7 @@ struct ScriptPtr3
 // The intermediate ZDoom version
 struct ScriptPtr1
 {
-	WORD Number;
+	SWORD Number;
 	WORD Type;
 	DWORD Address;
 	DWORD ArgCount;