diff --git a/ltp/fsx.c b/ltp/fsx.c
index 28f109cd..a7b36c14 100644
--- a/ltp/fsx.c
+++ b/ltp/fsx.c
@@ -20,6 +20,7 @@
 #include <strings.h>
 #include <sys/file.h>
 #include <sys/mman.h>
+#include <stdbool.h>
 #ifdef HAVE_ERR_H
 #include <err.h>
 #endif