diff --git a/archival/libunarchive/data_extract_to_stdout.c b/archival/libunarchive/data_extract_to_stdout.c
index d4137a1a8..df2bca6ef 100644
--- a/archival/libunarchive/data_extract_to_stdout.c
+++ b/archival/libunarchive/data_extract_to_stdout.c
@@ -15,6 +15,7 @@
  */
 
 #include "unarchive.h"
+#include <unistd.h>
 
 extern void data_extract_to_stdout(archive_handle_t *archive_handle)
 {
diff --git a/libbb/dump.c b/libbb/dump.c
index 52a6c063b..7ef559513 100644
--- a/libbb/dump.c
+++ b/libbb/dump.c
@@ -24,6 +24,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <ctype.h>		/* for isdigit() */
 #include "libbb.h"
 #include "dump.h"
diff --git a/libbb/print_file.c b/libbb/print_file.c
index 8f85cb4d6..963db1416 100644
--- a/libbb/print_file.c
+++ b/libbb/print_file.c
@@ -21,6 +21,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include "libbb.h"
 
 extern void bb_xprint_and_close_file(FILE *file)