clean up for unix port
diff --git a/src/lib9/fmt/fmtlock.c b/src/lib9/fmt/fmtlock.c
index fffe81c..7501ce4 100644
--- a/src/lib9/fmt/fmtlock.c
+++ b/src/lib9/fmt/fmtlock.c
@@ -12,6 +12,7 @@
  * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
  */
 #include <stdarg.h>
+#include "plan9.h"
 #include "fmt.h"
 #include "fmtdef.h"