diff --git a/ChangeLog b/ChangeLog
index 1211cc7..8b86cfc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+libisofs-1.5.6.pl01.tar.gz Mon Jun 12 2023
+===============================================================================
+* Bug fix: On non-GNU/Linux systems ssize_t was not defined in rockridge.h .
+           Report and fix proposal by Rui Chen.
+
 libisofs-1.5.6.tar.gz Wed Jun 07 2023
 ===============================================================================
 * Bug fix: iso_write_opts_set_part_like_isohybrid() did not cause a MBR
diff --git a/libisofs/changelog.txt b/libisofs/changelog.txt
index 40480d8..523eeb9 100644
--- a/libisofs/changelog.txt
+++ b/libisofs/changelog.txt
@@ -933,7 +933,7 @@ configure.ac
 libisofs/libisofs.h
 Version leap to 1.5.6
 
-07 Jun 2023  []
+07 Jun 2023  [170318c]
 ChangeLog
 libisofs/changelog.txt
 Updated change log
@@ -957,6 +957,18 @@ Updated change log
            exactly at a block boundary
 
 
+12 Jun 2023  [branch-1.5.6.pl01: ]
+libisofs/rockridge.h
+ChangeLog
+libisofs/changelog.txt
+Bug fix: On non-GNU/Linux systems ssize_t was not defined in rockridge.h .
+         Report and fix proposal by Rui Chen.
+
+------------------------------- release - libisofs-1.5.6.pl01 - 12 Jun 2023
+* Bug fix: On non-GNU/Linux systems ssize_t was not defined in rockridge.h .
+           Report and fix proposal by Rui Chen.
+
+
 ------------------------------------------------------------------------
 Todo about iso_read_image_feature_named() :
 Declared but not yet filled:
diff --git a/libisofs/rockridge.h b/libisofs/rockridge.h
index 5649eb7..b03189d 100644
--- a/libisofs/rockridge.h
+++ b/libisofs/rockridge.h
@@ -41,6 +41,9 @@
 
 #include "ecma119.h"
 
+/* For ssize_t */
+#include <unistd.h>
+
 
 #define SUSP_SIG(entry, a, b) ((entry->sig[0] == a) && (entry->sig[1] == b))