diff --git a/manual/tracy.tex b/manual/tracy.tex
index afff202a..202f77c6 100644
--- a/manual/tracy.tex
+++ b/manual/tracy.tex
@@ -1121,7 +1121,7 @@ enum SubSystems
 ...
 
 // Preferably a define in the build system
-#define SUBSYSTEMS Sys_Physics | Sys_NasalDemons
+#define SUBSYSTEMS (Sys_Physics | Sys_NasalDemons)
 
 ...