diff --git a/util-linux/mkswap.c b/util-linux/mkswap.c
index e7fab4e..5b908da 100644
--- a/util-linux/mkswap.c
+++ b/util-linux/mkswap.c
@@ -48,7 +48,7 @@
 
 #ifndef _IO
 /* pre-1.3.45 */
-#define BLKGETSIZE 0x1260
+static const int BLKGETSIZE = 0x1260;
 #else
 /* same on i386, m68k, arm; different on alpha, mips, sparc, ppc */
 #define BLKGETSIZE _IO(0x12,96)