diff --git a/type/__jool/explorer/alpine-kernel-modules b/type/__jool/explorer/alpine-kernel-modules
index e3a1a35..581d63a 100755
--- a/type/__jool/explorer/alpine-kernel-modules
+++ b/type/__jool/explorer/alpine-kernel-modules
@@ -10,4 +10,10 @@ case $(uname -r) in
 *-lts)
 	printf "jool-modules-lts"
 	;;
+*)
+	cat <<- EOF >&2
+	Incompatible kernel version found - could not install jool kernel
+	modules. Please use one of linux-lts or linux-virt.
+	EOF
+	exit 1
 esac
diff --git a/type/__jool/parameter/boolean b/type/__jool/parameter/boolean
deleted file mode 100644
index 73b3d4e..0000000
--- a/type/__jool/parameter/boolean
+++ /dev/null
@@ -1 +0,0 @@
-vm