diff --git a/Makefile.inc1 b/Makefile.inc1
index 7efa2437474..3d9deb86374 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -1140,6 +1140,8 @@ BUILDKERNELS+=	${_kernel}
 .if empty(INSTALLKERNEL) && !defined(NO_INSTALLKERNEL)
 INSTALLKERNEL= ${_kernel}
 .endif
+.else
+.error Missing KERNCONF ${KERNCONFDIR}/${_kernel}
 .endif
 .endfor