diff --git a/lib/libc/gen/ualarm.3 b/lib/libc/gen/ualarm.3
index 361319a3c830..4686d0703541 100644
--- a/lib/libc/gen/ualarm.3
+++ b/lib/libc/gen/ualarm.3
@@ -42,8 +42,8 @@
 .Lb libc
 .Sh SYNOPSIS
 .In unistd.h
-.Ft u_int
-.Fn ualarm "u_int microseconds" "u_int interval"
+.Ft useconds_t
+.Fn ualarm "useconds_t microseconds" "useconds_t interval"
 .Sh DESCRIPTION
 .Bf -symbolic
 This is a simplified interface to
diff --git a/lib/libc/gen/ualarm.c b/lib/libc/gen/ualarm.c
index a0048739a37a..f56a70d9c4fc 100644
--- a/lib/libc/gen/ualarm.c
+++ b/lib/libc/gen/ualarm.c
@@ -47,10 +47,10 @@ __FBSDID("$FreeBSD$");
  * If ``reload'' is non-zero, keep generating SIGALRM
  * every ``reload'' microseconds after the first signal.
  */
-unsigned
+useconds_t
 ualarm(usecs, reload)
-	unsigned usecs;
-	unsigned reload;
+	useconds_t usecs;
+	useconds_t reload;
 {
 	struct itimerval new, old;
 
diff --git a/lib/libc/gen/usleep.3 b/lib/libc/gen/usleep.3
index 807e7c53bc90..ffdc9223b71d 100644
--- a/lib/libc/gen/usleep.3
+++ b/lib/libc/gen/usleep.3
@@ -43,7 +43,7 @@
 .Sh SYNOPSIS
 .In unistd.h
 .Ft int
-.Fn usleep "unsigned int microseconds"
+.Fn usleep "useconds_t microseconds"
 .Sh DESCRIPTION
 The
 .Fn usleep
diff --git a/lib/libc/gen/usleep.c b/lib/libc/gen/usleep.c
index 7de9d94406bb..95c36a8558bc 100644
--- a/lib/libc/gen/usleep.c
+++ b/lib/libc/gen/usleep.c
@@ -44,7 +44,7 @@ __FBSDID("$FreeBSD$");
 
 int
 usleep(useconds)
-	unsigned int useconds;
+	useconds_t useconds;
 {
 	struct timespec time_to_sleep;