diff --git a/Makefile.am b/Makefile.am
index 4bc92d554..7463c147c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -45,3 +45,6 @@ install-exec-hook:
 	rm -f ${DESTDIR}${moduledir}/*.dll.a
 	rm -f ${DESTDIR}${moduledir}/autoload/*.dll.a
 	rm -f ${DESTDIR}${moduledir}/extensions/*.dll.a
+
+clean-local:
+	rm -f include/serno.h
diff --git a/librb/Makefile.am b/librb/Makefile.am
index a21a3026f..cfddf5d73 100644
--- a/librb/Makefile.am
+++ b/librb/Makefile.am
@@ -16,3 +16,5 @@ include/serno.h:
 		echo '#define DATECODE 0UL' >>include/serno.h; \
 	fi
 
+clean-local:
+	rm -f include/serno.h
diff --git a/librb/include/serno.h b/librb/include/serno.h
deleted file mode 100644
index 7ab979503..000000000
--- a/librb/include/serno.h
+++ /dev/null
@@ -1,2 +0,0 @@
-#define SERNO "20160307-81204be"
-#define DATECODE 1457395822UL