diff --git a/kernel/Makefile b/kernel/Makefile
index 08ba8a6abd1cd0ba448f0cac4a30f82768c06da5..58c6f111267e383c18cf3618fcb9902e6696a2ad 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -132,3 +132,52 @@ quiet_cmd_timeconst  = TIMEC   $@
 targets += timeconst.h
 $(obj)/timeconst.h: $(src)/timeconst.pl FORCE
 	$(call if_changed,timeconst)
+
+ifeq ($(CONFIG_MODULE_SIG),y)
+
+###############################################################################
+#
+# If module signing is requested, say by allyesconfig, but a key has not been
+# supplied, then one will need to be generated to make sure the build does not
+# fail and that the kernel may be used afterwards.
+#
+###############################################################################
+signing_key.priv signing_key.x509: x509.genkey
+	@echo "###"
+	@echo "### Now generating an X.509 key pair to be used for signing modules."
+	@echo "###"
+	@echo "### If this takes a long time, you might wish to run rngd in the"
+	@echo "### background to keep the supply of entropy topped up.  It"
+	@echo "### needs to be run as root, and should use a hardware random"
+	@echo "### number generator if one is available, eg:"
+	@echo "###"
+	@echo "###     rngd -r /dev/hwrandom"
+	@echo "###"
+	openssl req -new -nodes -utf8 -sha1 -days 36500 -batch \
+		-x509 -config x509.genkey \
+		-outform DER -out signing_key.x509 \
+		-keyout signing_key.priv
+	@echo "###"
+	@echo "### Key pair generated."
+	@echo "###"
+
+x509.genkey:
+	@echo Generating X.509 key generation config
+	@echo  >x509.genkey "[ req ]"
+	@echo >>x509.genkey "default_bits = 4096"
+	@echo >>x509.genkey "distinguished_name = req_distinguished_name"
+	@echo >>x509.genkey "prompt = no"
+	@echo >>x509.genkey "x509_extensions = myexts"
+	@echo >>x509.genkey
+	@echo >>x509.genkey "[ req_distinguished_name ]"
+	@echo >>x509.genkey "O = Magrathea"
+	@echo >>x509.genkey "CN = Glacier signing key"
+	@echo >>x509.genkey "emailAddress = slartibartfast@magrathea.h2g2"
+	@echo >>x509.genkey
+	@echo >>x509.genkey "[ myexts ]"
+	@echo >>x509.genkey "basicConstraints=critical,CA:FALSE"
+	@echo >>x509.genkey "keyUsage=digitalSignature"
+	@echo >>x509.genkey "subjectKeyIdentifier=hash"
+	@echo >>x509.genkey "authorityKeyIdentifier=keyid"
+endif
+CLEAN_FILES += signing_key.priv signing_key.x509 x509.genkey