diff --git a/src/doomdef.h b/src/doomdef.h
index fb2f020b75bd153b139e233554046c7a7fecfda8..825f774d7ca38c9079908ba4e879084b3a45b5ae 100644
--- a/src/doomdef.h
+++ b/src/doomdef.h
@@ -173,7 +173,7 @@ extern char logfilename[1024];
 #define MAXSKINS 1024
 #define SKINNAMESIZE 16
 #define MAXSKINUNAVAILABLE 128
-#define MAXAVAILABILITY MAXSKINUNAVAILABLE/8
+#define MAXAVAILABILITY (MAXSKINUNAVAILABLE / 8)
 
 #define COLORRAMPSIZE 16
 #define MAXCOLORNAME 32