diff --git a/ChangeLog b/ChangeLog
index 59281cf9..5d2827e6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,10 @@ Kjetil S.Matheussen
   Jackdmp changes log
 ---------------------------
 
+2007-11-20 Stephane Letz  <letz@grame.fr>
+
+	* Correct CheckPort in JackAPI.cpp.
+
 2007-11-15 Stephane Letz  <letz@grame.fr>
 
 	* Move OSX start/stop notification mechanism in Jackdmp.cpp.
diff --git a/common/JackAPI.cpp b/common/JackAPI.cpp
index 7da76105..fb2a7dca 100644
--- a/common/JackAPI.cpp
+++ b/common/JackAPI.cpp
@@ -221,7 +221,7 @@ inline double rint(double nr)
 
 static inline bool CheckPort(jack_port_id_t port_index)
 {
-    return (port_index < PORT_NUM);
+    return (port_index > 0 && port_index < PORT_NUM);
 }
 
 static inline bool CheckBufferSize(jack_nframes_t buffer_size)