diff --git a/asminc/stdio.inc b/asminc/stdio.inc
index e2f1beff9..ab9d86d2c 100644
--- a/asminc/stdio.inc
+++ b/asminc/stdio.inc
@@ -42,15 +42,15 @@ _IONBF		= 2
 BUFSIZ		= 256
 EOF 	      	= -1
 .if .defined(__APPLE2__) .or .defined(__APPLE2ENH__)
-FILENAME_MAX	= 64
+FILENAME_MAX	= 64+1
 .elseif .defined(__ATARI__)
-FILENAME_MAX	= 12
+FILENAME_MAX	= 12+1
 .elseif .defined(__LUNIX__)
-FILENAME_MAX    = 80
+FILENAME_MAX    = 80+1
 .else
-FILENAME_MAX	= 16
+FILENAME_MAX	= 16+1
 .endif
-L_tmpnam	= (FILENAME_MAX + 1)
+L_tmpnam	= FILENAME_MAX
 SEEK_CUR	= 0
 SEEK_END	= 1
 SEEK_SET	= 2
diff --git a/include/stdio.h b/include/stdio.h
index 771c4193b..8fac60d15 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -70,15 +70,15 @@ extern FILE* stderr;
 
 /* Standard defines that are platform dependent */
 #if defined(__APPLE2__) || defined(__APPLE2ENH__)
-#  define FILENAME_MAX	64
+#  define FILENAME_MAX	(64+1)
 #elif defined(__ATARI__)
-#  define FILENAME_MAX	12
+#  define FILENAME_MAX	(12+1)
 #elif defined(__LUNIX__)
-#  define FILENAME_MAX  80
+#  define FILENAME_MAX  (80+1)
 #else
-#  define FILENAME_MAX  16
+#  define FILENAME_MAX  (16+1)
 #endif
-#define L_tmpnam	(FILENAME_MAX + 1)
+#define L_tmpnam	FILENAME_MAX