diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index 11700621de..a573c8274c 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -5307,7 +5307,7 @@ libxlDiskPathToID(const char *virtpath)
     return id;
 }
 
-#define LIBXL_VBD_SECTOR_SIZE 512
+# define LIBXL_VBD_SECTOR_SIZE 512
 
 static int
 libxlDiskSectorSize(int domid, int devno)