diff --git a/cmdline/elem.c b/cmdline/elem.c
index bd255a4d..c33baee2 100644
--- a/cmdline/elem.c
+++ b/cmdline/elem.c
@@ -737,7 +737,9 @@ struct snapraid_disk* disk_alloc(const char* name, const char* dir, uint64_t dev
 	/* ensure that the dir terminate with "/" if it isn't empty */
 	pathslash(disk->dir, sizeof(disk->dir));
 
+#if HAVE_PTHREAD
 	thread_mutex_init(&disk->fs_mutex, 0);
+#endif
 
 	disk->smartctl[0] = 0;
 	disk->device = dev;
@@ -782,19 +784,29 @@ void disk_free(struct snapraid_disk* disk)
 	tommy_list_foreach(&disk->dirlist, (tommy_foreach_func*)dir_free);
 	tommy_hashdyn_done(&disk->dirset);
 
+#if HAVE_PTHREAD
 	thread_mutex_destroy(&disk->fs_mutex);
+#endif
 
 	free(disk);
 }
 
 static inline void fs_lock(struct snapraid_disk* disk)
 {
+#if HAVE_PTHREAD
 	thread_mutex_lock(&disk->fs_mutex);
+#else
+	(void)disk;
+#endif
 }
 
 static inline void fs_unlock(struct snapraid_disk* disk)
 {
+#if HAVE_PTHREAD
 	thread_mutex_unlock(&disk->fs_mutex);
+#else
+	(void)disk;
+#endif
 }
 
 struct chunk_disk_empty {
diff --git a/cmdline/elem.h b/cmdline/elem.h
index ba005329..c9f13974 100644
--- a/cmdline/elem.h
+++ b/cmdline/elem.h
@@ -355,6 +355,7 @@ struct snapraid_disk {
 	int mapping_idx; /**< Index in the mapping vector. Used only as buffer when writing the content file. */
 	int skip_access; /**< If the disk is inaccessible and it should be skipped. */
 
+#if HAVE_PTHREAD
 	/**
 	 * Mutex for protecting the filesystem structure.
 	 *
@@ -365,6 +366,7 @@ struct snapraid_disk {
 	 * change during multithread processing.
 	 */
 	pthread_mutex_t fs_mutex;
+#endif
 
 	/**
 	 * Mapping of chunks in the parity.
diff --git a/cmdline/io.c b/cmdline/io.c
index d4af5fb5..614a1a6a 100644
--- a/cmdline/io.c
+++ b/cmdline/io.c
@@ -19,18 +19,6 @@
 
 #include "io.h"
 
-/**
- * At now pthread is required.
- */
-#if !HAVE_PTHREAD
-#error Pthread library is required for InputOutput!
-#endif
-
-static inline int io_thread(struct snapraid_io* io)
-{
-	return io->io_max > 1;
-}
-
 /**
  * Get the next block position to process.
  */
@@ -273,6 +261,9 @@ static void io_stop_mono(struct snapraid_io* io)
 /*****************************************************************************/
 /* multi thread */
 
+/* disable multithread if pthread is not present */
+#if HAVE_PTHREAD
+
 /**
  * Get the next task to work on for a reader.
  *
@@ -847,6 +838,8 @@ static void io_stop_thread(struct snapraid_io* io)
 	}
 }
 
+#endif
+
 /*****************************************************************************/
 /* global */
 
@@ -862,6 +855,8 @@ void io_init(struct snapraid_io* io, struct snapraid_state* state,
 	size_t allocated;
 
 	io->state = state;
+
+#if HAVE_PTHREAD
 	if (io_cache == 0) {
 		/* default is 8 MiB of cache */
 		/* this seems to be a good tradeoff between speed and memory usage */
@@ -873,6 +868,12 @@ void io_init(struct snapraid_io* io, struct snapraid_state* state,
 	} else {
 		io->io_max = io_cache;
 	}
+#else
+	(void)io_cache;
+
+	/* without pthread force the mono thread mode */
+	io->io_max = 1;
+#endif
 
 	assert(io->io_max == 1 || (io->io_max >= IO_MIN && io->io_max <= IO_MAX));
 
@@ -943,7 +944,8 @@ void io_init(struct snapraid_io* io, struct snapraid_state* state,
 		worker->buffer_skew = handle_max;
 	}
 
-	if (io_thread(io)) {
+#if HAVE_PTHREAD
+	if (io->io_max > 1) {
 		io_read_next = io_read_next_thread;
 		io_write_preset = io_write_preset_thread;
 		io_write_next = io_write_next_thread;
@@ -959,7 +961,9 @@ void io_init(struct snapraid_io* io, struct snapraid_state* state,
 		thread_cond_init(&io->read_sched, 0);
 		thread_cond_init(&io->write_done, 0);
 		thread_cond_init(&io->write_sched, 0);
-	} else {
+	} else
+#endif
+	{
 		io_read_next = io_read_next_mono;
 		io_write_preset = io_write_preset_mono;
 		io_write_next = io_write_next_mono;
@@ -986,12 +990,14 @@ void io_done(struct snapraid_io* io)
 	free(io->writer_map);
 	free(io->writer_list);
 
-	if (io_thread(io)) {
+#if HAVE_PTHREAD
+	if (io->io_max > 1) {
 		thread_mutex_destroy(&io->io_mutex);
 		thread_cond_destroy(&io->read_done);
 		thread_cond_destroy(&io->read_sched);
 		thread_cond_destroy(&io->write_done);
 		thread_cond_destroy(&io->write_sched);
 	}
+#endif
 }
 
diff --git a/cmdline/snapraid.c b/cmdline/snapraid.c
index eeffb5fe..38b89b1a 100644
--- a/cmdline/snapraid.c
+++ b/cmdline/snapraid.c
@@ -814,7 +814,9 @@ int main(int argc, char* argv[])
 			opt.force_stats = 1;
 			break;
 		case OPT_TEST_COND_SIGNAL_OUTSIDE :
+#if HAVE_PTHREAD
 			thread_cond_signal_outside = 1;
+#endif
 			break;
 		default :
 			/* LCOV_EXCL_START */