diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 18f916b..d611acf 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -202,8 +202,10 @@
 
 .. data:: executable
 
-   A string giving the name of the executable binary for the Python interpreter, on
-   systems where this makes sense.
+   A string giving the absolute path of the executable binary for the Python
+   interpreter, on systems where this makes sense. If Python is unable to retrieve
+   the real path to its executable, :data:`sys.executable` will be an empty string
+   or ``None``.
 
 
 .. function:: exit([arg])