diff --git a/cmd/cmount/fs.go b/cmd/cmount/fs.go
index ae91e91ab..db4b78862 100644
--- a/cmd/cmount/fs.go
+++ b/cmd/cmount/fs.go
@@ -1,6 +1,6 @@
 // +build cmount
 // +build cgo
-// +build linux darwin freebsd windows
+// +build linux darwin freebsd openbsd windows
 
 package cmount
 
@@ -8,6 +8,7 @@ import (
 	"io"
 	"os"
 	"path"
+	"runtime"
 	"sync"
 	"time"
 
@@ -225,6 +226,12 @@ func (fsys *FS) Readdir(dirPath string,
 	// We can't seek in directories and FUSE should know that so
 	// return an error if ofst is ever set.
 	if ofst > 0 {
+		// However openbsd doesn't seem to know this - perhaps a bug in its
+		// FUSE implementation or a bug in cgofuse?
+		// See: https://github.com/billziss-gh/cgofuse/issues/49
+		if runtime.GOOS == "openbsd" {
+			return 0
+		}
 		return -fuse.ESPIPE
 	}
 
diff --git a/cmd/cmount/mount.go b/cmd/cmount/mount.go
index 50c755985..49bee8eee 100644
--- a/cmd/cmount/mount.go
+++ b/cmd/cmount/mount.go
@@ -4,7 +4,7 @@
 
 // +build cmount
 // +build cgo
-// +build linux darwin freebsd windows
+// +build linux darwin freebsd openbsd windows
 
 package cmount
 
@@ -37,13 +37,17 @@ func mountOptions(VFS *vfs.VFS, device string, mountpoint string, opt *mountlib.
 	options = []string{
 		"-o", "fsname=" + device,
 		"-o", "subtype=rclone",
-		"-o", fmt.Sprintf("max_readahead=%d", opt.MaxReadAhead),
 		"-o", fmt.Sprintf("attr_timeout=%g", opt.AttrTimeout.Seconds()),
-		// This causes FUSE to supply O_TRUNC with the Open
-		// call which is more efficient for cmount.  However
-		// it does not work with cgofuse on Windows with
-		// WinFSP so cmount must work with or without it.
-		"-o", "atomic_o_trunc",
+	}
+	if runtime.GOOS != "openbsd" {
+		options = append(options,
+			"-o", fmt.Sprintf("max_readahead=%d", opt.MaxReadAhead),
+			// This causes FUSE to supply O_TRUNC with the Open
+			// call which is more efficient for cmount.  However
+			// it does not work with cgofuse on Windows with
+			// WinFSP so cmount must work with or without it.
+			"-o", "atomic_o_trunc",
+		)
 	}
 	if opt.DebugFUSE {
 		options = append(options, "-o", "debug")
diff --git a/cmd/cmount/mount_test.go b/cmd/cmount/mount_test.go
index bb8b507b8..d68d2af20 100644
--- a/cmd/cmount/mount_test.go
+++ b/cmd/cmount/mount_test.go
@@ -1,6 +1,6 @@
 // +build cmount
 // +build cgo
-// +build linux darwin freebsd windows
+// +build linux darwin freebsd openbsd windows
 // +build !race !windows
 
 // FIXME this doesn't work with the race detector under Windows either
diff --git a/cmd/cmount/mount_unsupported.go b/cmd/cmount/mount_unsupported.go
index 57d820e22..d54565157 100644
--- a/cmd/cmount/mount_unsupported.go
+++ b/cmd/cmount/mount_unsupported.go
@@ -1,6 +1,6 @@
 // Build for cmount for unsupported platforms to stop go complaining
 // about "no buildable Go source files "
 
-// +build !linux,!darwin,!freebsd,!windows !cgo !cmount
+// +build !linux,!darwin,!freebsd,!openbsd,!windows !cgo !cmount
 
 package cmount