diff --git a/configure.ac b/configure.ac
index 607d8597..0e36336c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -347,6 +347,8 @@ AC_SUBST(PCIACCESS_LIBS)
 
 if test "x$UDEV" = xyes; then
 	AC_DEFINE(UDEV, 1, [Have UDEV support])
+else
+	AC_DEFINE(UDEV, 0)
 fi
 
 AC_CANONICAL_HOST
diff --git a/meson.build b/meson.build
index 826cd915..b90127aa 100644
--- a/meson.build
+++ b/meson.build
@@ -165,9 +165,9 @@ if _libkms != 'false'
   with_libkms = _libkms == 'true' or ['linux', 'freebsd', 'dragonfly'].contains(host_machine.system())
 endif
 
+config.set10('UDEV', with_udev)
 if with_udev
   dep_udev = dependency('udev')
-  config.set10('UDEV', true)
 else
   dep_udev = []
 endif
diff --git a/xf86drm.c b/xf86drm.c
index 344326db..9328bf5a 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -293,7 +293,7 @@ static int drmMatchBusID(const char *id1, const char *id2, int pci_domain_ok)
  * If any other failure happened then it will output error mesage using
  * drmMsg() call.
  */
-#if !defined(UDEV)
+#if !UDEV
 static int chown_check_return(const char *path, uid_t owner, gid_t group)
 {
         int rv;
@@ -332,7 +332,7 @@ static int drmOpenDevice(dev_t dev, int minor, int type)
     int             fd;
     mode_t          devmode = DRM_DEV_MODE, serv_mode;
     gid_t           serv_group;
-#if !defined(UDEV)
+#if !UDEV
     int             isroot  = !geteuid();
     uid_t           user    = DRM_DEV_UID;
     gid_t           group   = DRM_DEV_GID;
@@ -361,7 +361,7 @@ static int drmOpenDevice(dev_t dev, int minor, int type)
         devmode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
     }
 
-#if !defined(UDEV)
+#if !UDEV
     if (stat(DRM_DIR_NAME, &st)) {
         if (!isroot)
             return DRM_ERR_NOT_ROOT;
@@ -414,7 +414,7 @@ wait_for_udev:
     if (fd >= 0)
         return fd;
 
-#if !defined(UDEV)
+#if !UDEV
     /* Check if the device node is not what we expect it to be, and recreate it
      * and try again if so.
      */