diff --git a/Makefile.inc1 b/Makefile.inc1
index 1c6582d9d76..2f4d2fd9dda 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -1359,6 +1359,10 @@ BUILDKERNELS+=	${_kernel}
 .if empty(INSTALLKERNEL) && !defined(NO_INSTALLKERNEL)
 INSTALLKERNEL= ${_kernel}
 .endif
+.else
+.if make(buildkernel)
+.error Missing KERNCONF ${KERNCONFDIR}/${_kernel}
+.endif
 .endif
 .endfor
 
diff --git a/UPDATING b/UPDATING
index 69f9c7cbfd1..02384ebb6af 100644
--- a/UPDATING
+++ b/UPDATING
@@ -51,6 +51,13 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 12.x IS SLOW:
 
 ****************************** SPECIAL WARNING: ******************************
 
++20160714:
+	When building multiple kernels using KERNCONF, non-existent KERNCONF
+	files will produce an error and buildkernel will fail. Previously
+	missing KERNCONF files silently failed giving no indication as to
+	why, only to subsequently discover during installkernel that the
+	desired kernel was never built in the first place.
+
 20170912:
 	The default serial number format for CTL LUNs has changed.  This will
 	affect users who use /dev/diskid/* device nodes, or whose FibreChannel