Sigh: moving a header to toys.h isn't very useful if I forget to check in toys.h.
diff --git a/toys.h b/toys.h
index 25324d3..5ed8089 100644
--- a/toys.h
+++ b/toys.h
@@ -28,6 +28,7 @@
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/statvfs.h>
+#include <sys/sysinfo.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>