diff --git a/src/libdisk/mkfile b/src/libdisk/mkfile
index d3c909a7..cf657064 100644
--- a/src/libdisk/mkfile
+++ b/src/libdisk/mkfile
@@ -1,6 +1,7 @@
 <$PLAN9/src/mkhdr
 
 OFILES=\
+	disk.$O\
 	proto.$O\
 
 HFILES=$PLAN9/include/disk.h