diff --git a/lib/libc/sys/madvise.2 b/lib/libc/sys/madvise.2
index d3b21241267..4326389b1eb 100644
--- a/lib/libc/sys/madvise.2
+++ b/lib/libc/sys/madvise.2
@@ -40,7 +40,7 @@
 .Sh SYNOPSIS
 .Fd #include <sys/types.h>
 .Fd #include <sys/mman.h>
-.Fn madvise "caddr_t addr" "int len" "int behav"
+.Fn madvise "caddr_t addr" "size_t len" "int behav"
 .Sh DESCRIPTION
 The
 .Fn madvise
diff --git a/lib/libc/sys/mincore.2 b/lib/libc/sys/mincore.2
index bd6d9617eaf..a51fcc9fc46 100644
--- a/lib/libc/sys/mincore.2
+++ b/lib/libc/sys/mincore.2
@@ -40,7 +40,7 @@
 .Sh SYNOPSIS
 .Fd #include <sys/types.h>
 .Fd #include <sys/mman.h>
-.Fn mincore "caddr_t addr" "int len" "char *vec"
+.Fn mincore "caddr_t addr" "size_t len" "char *vec"
 .Sh DESCRIPTION
 The
 .Fn mincore
diff --git a/lib/libc/sys/mprotect.2 b/lib/libc/sys/mprotect.2
index c0ad2df138c..4ddd65d5e8a 100644
--- a/lib/libc/sys/mprotect.2
+++ b/lib/libc/sys/mprotect.2
@@ -40,7 +40,7 @@
 .Sh SYNOPSIS
 .Fd #include <sys/types.h>
 .Fd #include <sys/mman.h>
-.Fn mprotect "caddr_t addr" "int len" "int prot"
+.Fn mprotect "caddr_t addr" "size_t len" "int prot"
 .Sh DESCRIPTION
 The
 .Fn mprotect
diff --git a/lib/libc/sys/msync.2 b/lib/libc/sys/msync.2
index 88dd7f79fae..409dd08b35a 100644
--- a/lib/libc/sys/msync.2
+++ b/lib/libc/sys/msync.2
@@ -40,7 +40,7 @@
 .Sh SYNOPSIS
 .Fd #include <sys/types.h>
 .Fd #include <sys/mman.h>
-.Fn msync "caddr_t addr" "int len" "int flags"
+.Fn msync "caddr_t addr" "size_t len" "int flags"
 .Sh DESCRIPTION
 The
 .Fn msync