diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index b059b86aee68ceb63e06bc0d8e9ec680686e6bd4..e50c6cd1ff25ce4d65e0ebd854d052c3d1160a2a 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2399,7 +2399,6 @@ static void init_threaded_search(void)
 	pthread_mutex_init(&cache_mutex, NULL);
 	pthread_mutex_init(&progress_mutex, NULL);
 	pthread_cond_init(&progress_cond, NULL);
-	pthread_mutex_init(&to_pack.lock, NULL);
 	old_try_to_free_routine = set_try_to_free_routine(try_to_free_from_threads);
 }
 
diff --git a/pack-objects.c b/pack-objects.c
index 7e624c30ebd7f344d711b608b29b2d48d21a1ba0..b6cdbb0166fb5a3d6af3cfda2e7e259e3d54abe8 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -148,6 +148,9 @@ void prepare_packing_data(struct packing_data *pdata)
 					     1U << OE_SIZE_BITS);
 	pdata->oe_delta_size_limit = git_env_ulong("GIT_TEST_OE_DELTA_SIZE",
 						   1UL << OE_DELTA_SIZE_BITS);
+#ifndef NO_PTHREADS
+	pthread_mutex_init(&pdata->lock, NULL);
+#endif
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,
diff --git a/pack-objects.h b/pack-objects.h
index 2ca39cfcfe26aea164fc4173c49f0ffd05d4ef04..86ee93feb4f7d14518ed1ffe9cac8d8a7cd817fe 100644
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -377,7 +377,7 @@ static inline unsigned long oe_delta_size(struct packing_data *pack,
 		return e->delta_size_;
 
 	/*
-	 * pack->detla_size[] can't be NULL because oe_set_delta_size()
+	 * pack->delta_size[] can't be NULL because oe_set_delta_size()
 	 * must have been called when a new delta is saved with
 	 * oe_set_delta().
 	 * If oe_delta() returns NULL (i.e. default state, which means
diff --git a/t/t5321-pack-large-objects.sh b/t/t5321-pack-large-objects.sh
new file mode 100755
index 0000000000000000000000000000000000000000..a75eab87d36136de6484a988b712bfac03dd181d
--- /dev/null
+++ b/t/t5321-pack-large-objects.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+#
+# Copyright (c) 2018 Johannes Schindelin
+#
+
+test_description='git pack-object with "large" deltas
+
+'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-pack.sh
+
+# Two similar-ish objects that we have computed deltas between.
+A=01d7713666f4de822776c7622c10f1b07de280dc
+B=e68fe8129b546b101aee9510c5328e7f21ca1d18
+
+test_expect_success 'setup' '
+	clear_packs &&
+	{
+		pack_header 2 &&
+		pack_obj $A $B &&
+		pack_obj $B
+	} >ab.pack &&
+	pack_trailer ab.pack &&
+	git index-pack --stdin <ab.pack
+'
+
+test_expect_success 'repack large deltas' '
+	printf "%s\\n" $A $B |
+	GIT_TEST_OE_DELTA_SIZE=2 git pack-objects tmp-pack
+'
+
+test_done