diff --git a/Makefile b/Makefile
index 97151e5f..cd66db93 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
 PACKAGES ?= mountinfo mount
 BINDIR ?= _build/bin
 CROSS ?= linux/arm linux/arm64 linux/ppc64le linux/s390x \
-	freebsd/amd64 darwin/amd64 darwin/arm64 windows/amd64
+	freebsd/amd64 openbsd/amd64 darwin/amd64 darwin/arm64 windows/amd64
 
 .PHONY: all
 all: lint test cross
diff --git a/mount/flags_freebsd.go b/mount/flags_bsd.go
similarity index 97%
rename from mount/flags_freebsd.go
rename to mount/flags_bsd.go
index a8840d4c..27d8440a 100644
--- a/mount/flags_freebsd.go
+++ b/mount/flags_bsd.go
@@ -1,4 +1,4 @@
-// +build freebsd
+// +build freebsd openbsd
 
 package mount
 
diff --git a/mount/mount_unix_test.go b/mount/mount_unix_test.go
index 9b111f16..e2b37f62 100644
--- a/mount/mount_unix_test.go
+++ b/mount/mount_unix_test.go
@@ -1,4 +1,4 @@
-// +build !windows,!darwin
+// +build !darwin,!windows
 
 package mount
 
diff --git a/mount/mounter_freebsd.go b/mount/mounter_bsd.go
similarity index 97%
rename from mount/mounter_freebsd.go
rename to mount/mounter_bsd.go
index f4e2e0bb..656b762f 100644
--- a/mount/mounter_freebsd.go
+++ b/mount/mounter_bsd.go
@@ -1,4 +1,4 @@
-// +build freebsd cgo
+// +build freebsd,cgo openbsd,cgo
 
 package mount
 
diff --git a/mount/mounter_linux_test.go b/mount/mounter_linux_test.go
index 9ba4857f..3dbcb77a 100644
--- a/mount/mounter_linux_test.go
+++ b/mount/mounter_linux_test.go
@@ -1,5 +1,3 @@
-// +build linux
-
 package mount
 
 import (
diff --git a/mount/mounter_unsupported.go b/mount/mounter_unsupported.go
index 41ac018a..e7ff5bd9 100644
--- a/mount/mounter_unsupported.go
+++ b/mount/mounter_unsupported.go
@@ -1,7 +1,7 @@
-// +build freebsd,!cgo
+// +build !linux,!freebsd,!openbsd,!windows freebsd,!cgo openbsd,!cgo
 
 package mount
 
 func mount(device, target, mType string, flag uintptr, data string) error {
-	panic("cgo required on freebsd")
+	panic("cgo required on freebsd and openbsd")
 }
diff --git a/mount/sharedsubtree_linux_test.go b/mount/sharedsubtree_linux_test.go
index 1e2a053e..aa671d0c 100644
--- a/mount/sharedsubtree_linux_test.go
+++ b/mount/sharedsubtree_linux_test.go
@@ -1,5 +1,3 @@
-// +build linux
-
 package mount
 
 import (
diff --git a/mountinfo/doc.go b/mountinfo/doc.go
index ffac661f..2694d4c6 100644
--- a/mountinfo/doc.go
+++ b/mountinfo/doc.go
@@ -1,6 +1,6 @@
 // Package mountinfo provides a set of functions to retrieve information about OS mounts.
 //
-// Currently it supports Linux. For historical reasons, there is also some support for FreeBSD,
+// Currently it supports Linux. For historical reasons, there is also some support for FreeBSD and OpenBSD,
 // and a shallow implementation for Windows, but in general this is Linux-only package, so
 // the rest of the document only applies to Linux, unless explicitly specified otherwise.
 //
diff --git a/mountinfo/mounted_unix.go b/mountinfo/mounted_unix.go
index c4d66b2f..efb03978 100644
--- a/mountinfo/mounted_unix.go
+++ b/mountinfo/mounted_unix.go
@@ -1,4 +1,4 @@
-// +build linux freebsd,cgo
+// +build linux freebsd,cgo openbsd,cgo
 
 package mountinfo
 
diff --git a/mountinfo/mountinfo_freebsd.go b/mountinfo/mountinfo_bsd.go
similarity index 93%
rename from mountinfo/mountinfo_freebsd.go
rename to mountinfo/mountinfo_bsd.go
index b30dc162..1d1484d4 100644
--- a/mountinfo/mountinfo_freebsd.go
+++ b/mountinfo/mountinfo_bsd.go
@@ -1,3 +1,5 @@
+// +build freebsd,cgo openbsd,cgo
+
 package mountinfo
 
 /*
@@ -54,7 +56,7 @@ func parseMountTable(filter FilterFunc) ([]*Info, error) {
 
 func mounted(path string) (bool, error) {
 	// Fast path: compare st.st_dev fields.
-	// This should always work for FreeBSD.
+	// This should always work for FreeBSD and OpenBSD.
 	mounted, err := mountedByStat(path)
 	if err == nil {
 		return mounted, nil
diff --git a/mountinfo/mountinfo_linux.go b/mountinfo/mountinfo_linux.go
index fd4fb341..f76b26c8 100644
--- a/mountinfo/mountinfo_linux.go
+++ b/mountinfo/mountinfo_linux.go
@@ -1,5 +1,3 @@
-// +build go1.13
-
 package mountinfo
 
 import (
diff --git a/mountinfo/mountinfo_linux_test.go b/mountinfo/mountinfo_linux_test.go
index b77fb571..5f4133fb 100644
--- a/mountinfo/mountinfo_linux_test.go
+++ b/mountinfo/mountinfo_linux_test.go
@@ -1,5 +1,3 @@
-// +build linux
-
 package mountinfo
 
 import (
diff --git a/mountinfo/mountinfo_unsupported.go b/mountinfo/mountinfo_unsupported.go
index b9acfbdc..d33ebca0 100644
--- a/mountinfo/mountinfo_unsupported.go
+++ b/mountinfo/mountinfo_unsupported.go
@@ -1,4 +1,4 @@
-// +build !windows,!linux,!freebsd freebsd,!cgo
+// +build !windows,!linux,!freebsd,!openbsd freebsd,!cgo openbsd,!cgo
 
 package mountinfo