Index: src/tests/concurrent/preempt.c
===================================================================
--- src/tests/concurrent/preempt.c	(revision 8ad653339f39e704e4be3cbd354de857c44a52f4)
+++ src/tests/concurrent/preempt.c	(revision 0f5605831af289410e02930b6965262873df0fc9)
@@ -1,4 +1,5 @@
 #include <kernel>
 #include <thread>
+#include <time>
 
 #ifndef PREEMPTION_RATE
Index: src/tests/concurrent/signal/block.c
===================================================================
--- src/tests/concurrent/signal/block.c	(revision 8ad653339f39e704e4be3cbd354de857c44a52f4)
+++ src/tests/concurrent/signal/block.c	(revision 0f5605831af289410e02930b6965262873df0fc9)
@@ -12,6 +12,5 @@
 #include <stdlib>
 #include <thread>
-
-#include <time.h>
+#include <time>
 
 #ifdef LONG_TEST
Index: src/tests/concurrent/signal/disjoint.c
===================================================================
--- src/tests/concurrent/signal/disjoint.c	(revision 8ad653339f39e704e4be3cbd354de857c44a52f4)
+++ src/tests/concurrent/signal/disjoint.c	(revision 0f5605831af289410e02930b6965262873df0fc9)
@@ -3,6 +3,5 @@
 #include <monitor>
 #include <thread>
-
-#include <time.h>
+#include <time>
 
 #ifdef LONG_TEST
Index: src/tests/concurrent/signal/wait.c
===================================================================
--- src/tests/concurrent/signal/wait.c	(revision 8ad653339f39e704e4be3cbd354de857c44a52f4)
+++ src/tests/concurrent/signal/wait.c	(revision 0f5605831af289410e02930b6965262873df0fc9)
@@ -10,6 +10,5 @@
 #include <stdlib>
 #include <thread>
-
-#include <time.h>
+#include <time>
 
 #ifdef LONG_TEST