https://bugs.gentoo.org/852119
--- a/libs-external/USI++/src/datalink.cc
+++ b/libs-external/USI++/src/datalink.cc
@@ -15,6 +15,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
+#include <ctime>
 #include <sys/ioctl.h>
 
 #ifdef IMMEDIATE
--- a/libs-external/USI++/src/tcp.cc
+++ b/libs-external/USI++/src/tcp.cc
@@ -16,6 +16,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
+#include <ctime>
 
 namespace usipp {