diff --git a/Makefile b/Makefile
index 531dd16..6ab99d8 100644
--- a/Makefile
+++ b/Makefile
@@ -1173,8 +1173,8 @@
 		  arch/*/include/generated .tmp_objdiff
 MRPROPER_FILES += .config .config.old .version .old_version \
 		  Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS \
-		  signing_key.priv signing_key.x509 x509.genkey		\
-		  extra_certificates signing_key.x509.keyid		\
+		  signing_key.pem signing_key.priv signing_key.x509	\
+		  x509.genkey extra_certificates signing_key.x509.keyid	\
 		  signing_key.x509.signer vmlinux-gdb.py
 
 # clean - Delete most, but leave enough to build external modules