diff --git a/AUTHORS b/AUTHORS
index a5463d1..ffaee3c 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 Numerous users of the Extension Language Kit (too many to mention them
 all) have contributed ideas, suggestions for improvements, bug reports,
diff --git a/BUGS b/BUGS
index 529066d..42fa72d 100644
--- a/BUGS
+++ b/BUGS
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 Generational/Incremental Garbage Collector
 
diff --git a/INSTALL b/INSTALL
index 81d2421..56eca39 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 Compilation and Installation Instructions for Elk
 -------------------------------------------------
diff --git a/MACHINES b/MACHINES
index efb9e2d..c41befa 100644
--- a/MACHINES
+++ b/MACHINES
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 Sun-3 and Sun-4, SunOS 4.1
 
diff --git a/MIGRATE b/MIGRATE
index 254c712..85411a2 100644
--- a/MIGRATE
+++ b/MIGRATE
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 This file lists changes in the interpreter kernel that affect the C/C++
 interface to applications using Elk and to Elk extensions, and (in
diff --git a/README b/README
index 9339024..76c8238 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 This is Elk 3.99, a pre-release of Elk 4.0, the Extension Language Kit.
 
diff --git a/TODO b/TODO
index fe6974b..d380827 100644
--- a/TODO
+++ b/TODO
@@ -1,4 +1,4 @@
-$Id: foo$
+$Id$
 
 Interpreter kernel
 
diff --git a/configure.ac b/configure.ac
index 2d65a87..acde3ff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,3 +1,5 @@
+# $Id$
+
 AC_INIT(src/main.c)
 
 AC_PREREQ(2.50)