diff --git a/mp b/mp
index d09f2cf55e8402240738af099cdfbfdc487e3837..32c4cd5fe10ad5b8429d747ef35314afb2675f9e 100755
--- a/mp
+++ b/mp
@@ -3,6 +3,7 @@
 set -e
 
 find src -name '*.o' -delete
+rm -f build/system.elf
 
 for i in info program; do
 	make "$@" $i
diff --git a/mpm b/mpm
index 6caa92d3b1d6d9c0899c8d7ba291aae12e61459a..4abd7df835fe5e3558b49a4404c6e76a8e0af18e 100755
--- a/mpm
+++ b/mpm
@@ -3,6 +3,7 @@
 set -e
 
 find src -name '*.o' -delete
+rm -f build/system.elf
 
 for i in info program monitor; do
 	make "$@" $i