diff --git a/kernel-module/xt_RTPENGINE.c b/kernel-module/xt_RTPENGINE.c
index c0358dc32..162f14d4f 100644
--- a/kernel-module/xt_RTPENGINE.c
+++ b/kernel-module/xt_RTPENGINE.c
@@ -34,7 +34,7 @@
 #include <linux/math64.h>
 #include <linux/kthread.h>
 #include <linux/wait.h>
-#if CONFIG_BTREE
+#ifdef CONFIG_BTREE
 #include <linux/btree.h>
 #define KERNEL_PLAYER
 #else