diff --git a/ANNOUNCE b/ANNOUNCE
index 55da1b332..769069eea 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -33,6 +33,8 @@ Version 1.6.14beta01 [September 14, 2014]
   Add "#include <setjmp.h>" to contrib/tools/pngfix.c (John Bowler)
 
 Version 1.6.14beta02 [September 14, 2014]
+  Define usleep() in contrib/gregbook/rpng2-x.c if not already defined
+    in unistd.h; fixes error introduced in libpng-1.6.13.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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diff --git a/CHANGES b/CHANGES
index 99b40ccf4..ab508b8ec 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4986,6 +4986,8 @@ Version 1.6.14beta01 [September 14, 2014]
   Add "#include <setjmp.h>" to contrib/tools/pngfix.c (John Bowler)
 
 Version 1.6.14beta02 [September 14, 2014]
+  Define usleep() in contrib/gregbook/rpng2-x.c if not already defined
+    in unistd.h; fixes error introduced in libpng-1.6.13.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/contrib/gregbook/rpng2-x.c b/contrib/gregbook/rpng2-x.c
index a146ef417..6e02c890d 100644
--- a/contrib/gregbook/rpng2-x.c
+++ b/contrib/gregbook/rpng2-x.c
@@ -103,9 +103,6 @@
 #define RESNAME   "rpng2"       /* our X resource application name */
 #define RESCLASS  "Rpng"       /* our X resource class name */
 
-/* This is temporary until the code is rewritten to use nanosleep(). */
-#define usleep(x) sleep(((x)+499999)/1000000)
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <ctype.h>
@@ -118,6 +115,11 @@
 #include <X11/Xos.h>
 #include <X11/keysym.h>   /* defines XK_* macros */
 
+/* This is temporary until the code is rewritten to use nanosleep(). */
+#ifndef usleep
+#  define usleep(x) sleep(((x)+499999)/1000000)
+#endif
+
 #ifdef VMS
 #  include <unistd.h>
 #endif