diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index d39193453..a71523706 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1972,8 +1972,6 @@ static void ll_find_deltas(struct object_entry **list, unsigned list_size,
 
 	init_threaded_search();
 
-	if (!delta_search_threads)	/* --threads=0 means autodetect */
-		delta_search_threads = online_cpus();
 	if (delta_search_threads <= 1) {
 		find_deltas(list, &list_size, window, depth, processed);
 		cleanup_threaded_search();
@@ -2685,6 +2683,10 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		pack_compression_level = Z_DEFAULT_COMPRESSION;
 	else if (pack_compression_level < 0 || pack_compression_level > Z_BEST_COMPRESSION)
 		die("bad pack compression level %d", pack_compression_level);
+
+	if (!delta_search_threads)	/* --threads=0 means autodetect */
+		delta_search_threads = online_cpus();
+
 #ifdef NO_PTHREADS
 	if (delta_search_threads != 1)
 		warning("no threads support, ignoring --threads");
diff --git a/thread-utils.h b/thread-utils.h
index 6fb98c333..d9a769d19 100644
--- a/thread-utils.h
+++ b/thread-utils.h
@@ -7,5 +7,9 @@
 extern int online_cpus(void);
 extern int init_recursive_mutex(pthread_mutex_t*);
 
+#else
+
+#define online_cpus() 1
+
 #endif
 #endif /* THREAD_COMPAT_H */