Index: sys/compat/linux/linux_futex.c
===================================================================
--- sys/compat/linux/linux_futex.c
+++ sys/compat/linux/linux_futex.c
@@ -989,6 +989,10 @@
 	uint32_t uval, nval, mval;
 	int error;
 
+	/* Check that futex address is a 32bit aligned. */
+	if (!__is_aligned(uaddr, sizeof(uint32_t)))
+		return (EINVAL);
+
 retry:
 	error = fueword32(uaddr, &uval);
 	if (error != 0)