diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c
index f326b9aa691..7c01586b4dd 100644
--- a/sys/kern/kern_umtx.c
+++ b/sys/kern/kern_umtx.c
@@ -2618,6 +2618,10 @@ do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
 			}
 		} else if (owner == UMUTEX_RB_NOTRECOV) {
 			error = ENOTRECOVERABLE;
+		} else if (owner == UMUTEX_CONTESTED) {
+			/* Spurious failure, retry. */
+			umtxq_unbusy_unlocked(&uq->uq_key);
+			continue;
 		}
 
 		if (try != 0)
@@ -2824,6 +2828,10 @@ do_set_ceiling(struct thread *td, struct umutex *m, uint32_t ceiling,
 		} else if (owner == UMUTEX_RB_NOTRECOV) {
 			error = ENOTRECOVERABLE;
 			break;
+		} else if (owner == UMUTEX_CONTESTED) {
+			/* Spurious failure, retry. */
+			umtxq_unbusy_unlocked(&uq->uq_key);
+			continue;
 		}
 
 		/*