diff --git a/src/core/iocalls.c b/src/core/iocalls.c
index f51f380..244da9a 100644
--- a/src/core/iocalls.c
+++ b/src/core/iocalls.c
@@ -472,6 +472,11 @@ LIB3270_EXPORT int lib3270_wait(H3270 *hSession, int seconds)
 	return 0;
 }
 
+LIB3270_EXPORT int wait_for_update(H3270 *hSession, int seconds)
+{
+	return errno = ENOTSUP;
+}
+
 LIB3270_EXPORT int lib3270_wait_for_ready(H3270 *hSession, int seconds)
 {
 	time_t	end = time(0)+seconds;
diff --git a/src/include/lib3270.h b/src/include/lib3270.h
index f8462db..7a7c7f7 100644
--- a/src/include/lib3270.h
+++ b/src/include/lib3270.h
@@ -998,7 +998,7 @@
 	LIB3270_EXPORT void * lib3270_get_user_data(H3270 *h);
 
 	/**
-	 * Wait for "N" seconds keeping main loop active.
+	 * @brief Wait for "N" seconds keeping main loop active.
 	 *
 	 * @param seconds	Number of seconds to wait.
 	 *
@@ -1006,6 +1006,14 @@
 	LIB3270_EXPORT int lib3270_wait(H3270 *hSession, int seconds);
 
 	/**
+	 * @brief Wait for "N" seconds or screen change; keeps main loop active.
+	 *
+	 * @param seconds	Number of seconds to wait.
+	 *
+	 */
+	LIB3270_EXPORT int wait_for_update(H3270 *hSession, int seconds);
+
+	/**
 	 * Wait "N" seconds for "ready" state.
 	 *
 	 * @param seconds	Number of seconds to wait.
--
libgit2 0.21.2