diff --git a/0003-Document-implicit-fallthrough.patch b/0003-Document-implicit-fallthrough.patch
new file mode 100644
index 0000000..c5a282c
--- /dev/null
+++ b/0003-Document-implicit-fallthrough.patch
@@ -0,0 +1,25 @@
+From 4b9e7cf3e869de36daf2ea705b9efef55ae87ef8 Mon Sep 17 00:00:00 2001
+From: Peter Jones <pjones@redhat.com>
+Date: Sat, 8 Jul 2017 16:31:18 -0400
+Subject: [PATCH] Document implicit fallthrough.
+
+Signed-off-by: Peter Jones <pjones@redhat.com>
+---
+ src/authvar.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/src/authvar.c b/src/authvar.c
+index ad659ca..03e0c47 100644
+--- a/src/authvar.c
++++ b/src/authvar.c
+@@ -511,6 +511,7 @@ main(int argc, char *argv[])
+ 	case IMPORT|SET:
+ 	case IMPORT|SIGN|SET:
+ 		fprintf(stderr, "authvar: not implemented\n");
++		/* fallthrough. */
+ 	case IMPORT|SIGN|EXPORT:
+ 	default:
+ 		fprintf(stderr, "authvar: invalid flags: ");
+-- 
+2.13.0
+
diff --git a/pesign.spec b/pesign.spec
index a7f38aa..74505a5 100644
--- a/pesign.spec
+++ b/pesign.spec
@@ -30,6 +30,7 @@ Source1: certs.tar.xz
 
 Patch0001: 0001-cms-kill-generate_integer-it-doesn-t-build-on-i686-a.patch
 Patch0002: 0002-Fix-command-line-parsing.patch
+Patch0003: 0003-Document-implicit-fallthrough.patch
 
 %description
 This package contains the pesign utility for signing UEFI binaries as