diff --git a/sys/dev/random/random_harvestq.c b/sys/dev/random/random_harvestq.c
--- a/sys/dev/random/random_harvestq.c
+++ b/sys/dev/random/random_harvestq.c
@@ -254,6 +254,28 @@
 	 */
 	npools = howmany(p_random_alg_context->ra_poolcount, RANDOM_KTHREAD_HZ);
 
+	/*-
+	 * If we're not seeded yet, attempt to perform a "full seed", filling
+	 * all of the PRNG's pools with entropy; if there is enough entropy
+	 * available from "fast" entropy sources this will allow us to finish
+	 * seeding and unblock the boot process immediately rather than being
+	 * stuck for a few seconds with random_kthread gradually collecting a
+	 * small chunk of entropy every 1 / RANDOM_KTHREAD_HZ seconds.
+	 *
+	 * The value 64 below is RANDOM_FORTUNA_DEFPOOLSIZE, i.e. chosen to
+	 * fill Fortuna's pools in the default configuration.  With another
+	 * PRNG or smaller pools for Fortuna, we might collect more entropy
+	 * than needed to fill the pools, but this is harmless; alternatively,
+	 * a different PRNG, larger pools, or fast entropy sources which are
+	 * not able to provide as much entropy as we request may result in the
+	 * not being fully seeded (and thus remaining blocked) but in that
+	 * case we will return here after 1 / RANDOM_KTHREAD_HZ seconds and
+	 * try again for a large amount of entropy.
+	 */
+	if (!p_random_alg_context->ra_seeded())
+		npools = howmany(p_random_alg_context->ra_poolcount * 64,
+		    sizeof(entropy));
+
 	/*
 	 * Step over all of live entropy sources, and feed their output
 	 * to the system-wide RNG.