diff --git a/libc-test/semver/netbsd.txt b/libc-test/semver/netbsd.txt
index 57e1cf5c4bd1b..677e37ea0a155 100644
--- a/libc-test/semver/netbsd.txt
+++ b/libc-test/semver/netbsd.txt
@@ -426,6 +426,17 @@ IFF_SIMPLEX
 IFF_UP
 IMAXBEL
 INIT_PROCESS
+IOCBASECMD
+IOCGROUP
+IOCGROUP_SHIFT
+IOCPARM_LEN
+IOCPARM_MASK
+IOCPARM_SHIFT
+IOC_DIRMASK
+IOC_IN
+IOC_INOUT
+IOC_OUT
+IOC_VOID
 IOV_MAX
 IPC_CREAT
 IPC_EXCL
@@ -1116,9 +1127,14 @@ XATTR_CREATE
 XATTR_REPLACE
 YESEXPR
 YESSTR
+_IO
+_IOC
 _IOFBF
 _IOLBF
 _IONBF
+_IOR
+_IOW
+_IOWR
 _PC_2_SYMLINKS
 _PC_ACL_EXTENDED
 _PC_FILESIZEBITS
diff --git a/libc-test/semver/openbsd.txt b/libc-test/semver/openbsd.txt
index f609a7b72cd45..6e452dadea797 100644
--- a/libc-test/semver/openbsd.txt
+++ b/libc-test/semver/openbsd.txt
@@ -267,6 +267,15 @@ IFF_SIMPLEX
 IFF_STATICARP
 IFF_UP
 IMAXBEL
+IOCBASECMD
+IOCGROUP
+IOCPARM_LEN
+IOCPARM_MASK
+IOC_DIRMASK
+IOC_IN
+IOC_INOUT
+IOC_OUT
+IOC_VOID
 IOV_MAX
 IPC_CREAT
 IPC_EXCL
@@ -908,9 +917,14 @@ WSTOPPED
 WTRAPPED
 YESEXPR
 YESSTR
+_IO
+_IOC
 _IOFBF
 _IOLBF
 _IONBF
+_IOR
+_IOW
+_IOWR
 _MAX_PAGE_SHIFT
 _PC_2_SYMLINKS
 _PC_ALLOC_SIZE_MIN
diff --git a/src/unix/bsd/netbsdlike/mod.rs b/src/unix/bsd/netbsdlike/mod.rs
index c95880ecb272c..4b66584b8e562 100644
--- a/src/unix/bsd/netbsdlike/mod.rs
+++ b/src/unix/bsd/netbsdlike/mod.rs
@@ -439,6 +439,34 @@ pub const MNT_NODEV: c_int = 0x00000010;
 pub const MNT_LOCAL: c_int = 0x00001000;
 pub const MNT_QUOTA: c_int = 0x00002000;
 
+// sys/ioccom.h in NetBSD and OpenBSD
+pub const IOCPARM_MASK: u32 = 0x1fff;
+
+pub const IOC_VOID: c_ulong = 0x20000000;
+pub const IOC_OUT: c_ulong = 0x40000000;
+pub const IOC_IN: c_ulong = 0x80000000;
+pub const IOC_INOUT: c_ulong = IOC_IN | IOC_OUT;
+pub const IOC_DIRMASK: c_ulong = 0xe0000000;
+
+pub const fn _IO(g: c_ulong, n: c_ulong) -> c_ulong {
+    _IOC(IOC_VOID, g, n, 0)
+}
+
+/// Build an ioctl number for an read-only ioctl.
+pub const fn _IOR<T>(g: c_ulong, n: c_ulong) -> c_ulong {
+    _IOC(IOC_OUT, g, n, mem::size_of::<T>() as c_ulong)
+}
+
+/// Build an ioctl number for an write-only ioctl.
+pub const fn _IOW<T>(g: c_ulong, n: c_ulong) -> c_ulong {
+    _IOC(IOC_IN, g, n, mem::size_of::<T>() as c_ulong)
+}
+
+/// Build an ioctl number for a read-write ioctl.
+pub const fn _IOWR<T>(g: c_ulong, n: c_ulong) -> c_ulong {
+    _IOC(IOC_INOUT, g, n, mem::size_of::<T>() as c_ulong)
+}
+
 pub const AF_UNSPEC: c_int = 0;
 pub const AF_LOCAL: c_int = 1;
 pub const AF_UNIX: c_int = AF_LOCAL;
diff --git a/src/unix/bsd/netbsdlike/netbsd/mod.rs b/src/unix/bsd/netbsdlike/netbsd/mod.rs
index a1d06ddd0dd7c..3d68da68674d6 100644
--- a/src/unix/bsd/netbsdlike/netbsd/mod.rs
+++ b/src/unix/bsd/netbsdlike/netbsd/mod.rs
@@ -1850,6 +1850,26 @@ pub const MNT_WAIT: c_int = 1;
 pub const MNT_NOWAIT: c_int = 2;
 pub const MNT_LAZY: c_int = 3;
 
+// sys/ioccom.h
+pub const IOCPARM_SHIFT: u32 = 16;
+pub const IOCGROUP_SHIFT: u32 = 8;
+
+pub const fn IOCPARM_LEN(x: u32) -> u32 {
+    (x >> IOCPARM_SHIFT) & crate::IOCPARM_MASK
+}
+
+pub const fn IOCBASECMD(x: u32) -> u32 {
+    x & (!(crate::IOCPARM_MASK << IOCPARM_SHIFT))
+}
+
+pub const fn IOCGROUP(x: u32) -> u32 {
+    (x >> IOCGROUP_SHIFT) & 0xff
+}
+
+pub const fn _IOC(inout: c_ulong, group: c_ulong, num: c_ulong, len: c_ulong) -> c_ulong {
+    (inout) | (((len) & crate::IOCPARM_MASK as c_ulong) << IOCPARM_SHIFT) | ((group) << IOCGROUP_SHIFT) | (num)
+}
+
 //<sys/timex.h>
 pub const CLOCK_PROCESS_CPUTIME_ID: crate::clockid_t = 2;
 pub const CLOCK_THREAD_CPUTIME_ID: crate::clockid_t = 4;
diff --git a/src/unix/bsd/netbsdlike/openbsd/mod.rs b/src/unix/bsd/netbsdlike/openbsd/mod.rs
index dc1e7af00e400..95854dfd561ee 100644
--- a/src/unix/bsd/netbsdlike/openbsd/mod.rs
+++ b/src/unix/bsd/netbsdlike/openbsd/mod.rs
@@ -1804,6 +1804,23 @@ pub const PF_R: u32 = 0x4;
 pub const PF_MASKOS: u32 = 0x0ff00000;
 pub const PF_MASKPROC: u32 = 0xf0000000;
 
+// sys/ioccom.h
+pub const fn IOCPARM_LEN(x: u32) -> u32 {
+    (x >> 16) & crate::IOCPARM_MASK
+}
+
+pub const fn IOCBASECMD(x: u32) -> u32 {
+    x & (!(crate::IOCPARM_MASK << 16))
+}
+
+pub const fn IOCGROUP(x: u32) -> u32 {
+    (x >> 8) & 0xff
+}
+
+pub const fn _IOC(inout: c_ulong, group: c_ulong, num: c_ulong, len: c_ulong) -> c_ulong {
+    (inout) | (((len) & crate::IOCPARM_MASK as c_ulong) << 16) | ((group) << 8) | (num)
+}
+
 // sys/mount.h
 pub const MNT_NOPERM: c_int = 0x00000020;
 pub const MNT_WXALLOWED: c_int = 0x00000800;