diff --git a/linux/Config.in b/linux/Config.in
index 583735ef43..be619d377e 100644
--- a/linux/Config.in
+++ b/linux/Config.in
@@ -40,6 +40,11 @@ config BR2_LINUX_KERNEL_CUSTOM_VERSION
 	  This option allows to use a specific official version from
 	  kernel.org, like 2.6.x, 2.6.x.y, 3.x.y, ...
 
+	  Note: you cannot use this option to select a _longterm_ 2.6
+	  kernel, because these kernels are not located at the standard
+	  URL at kernel.org. Instead, select "Custom tarball" and
+	  specify the right URL directly.
+
 config BR2_LINUX_KERNEL_CUSTOM_TARBALL
 	bool "Custom tarball"
 	help