diff --git a/HISTORY.rst b/HISTORY.rst
index 67e3a0935..3b00b3b9d 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -40,6 +40,8 @@ XXXX-XX-XX
   pre-emptively checked for `Process.nice()`_ (set), `Process.ionice()`_,
   (set), `Process.cpu_affinity()`_ (set), `Process.rlimit()`_
   (set), `Process.parent()`_.
+- 2308_, [OpenBSD]: `Process.threads()`_ always fail with AccessDenied (also as
+  root).
 
 5.9.5
 =====
diff --git a/psutil/arch/openbsd/proc.c b/psutil/arch/openbsd/proc.c
index 5c984fc53..96b85bc50 100644
--- a/psutil/arch/openbsd/proc.c
+++ b/psutil/arch/openbsd/proc.c
@@ -219,8 +219,15 @@ psutil_proc_threads(PyObject *self, PyObject *args) {
 
     kd = kvm_openfiles(0, 0, 0, O_RDONLY, errbuf);
     if (! kd) {
-        convert_kvm_err("kvm_openfiles()", errbuf);
-        goto error;
+        // Usually fails due to EPERM against /dev/mem. We retry with
+        // KVM_NO_FILES which apparently has the same effect.
+        // https://stackoverflow.com/questions/22369736/
+        psutil_debug("kvm_openfiles(O_RDONLY) failed");
+        kd = kvm_openfiles(NULL, NULL, NULL, KVM_NO_FILES, errbuf);
+        if (! kd) {
+            convert_kvm_err("kvm_openfiles()", errbuf);
+            goto error;
+        }
     }
 
     kp = kvm_getprocs(