diff --git a/ChangeLog b/ChangeLog
index 40beafa16..0958fd063 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2010-09-08  Robert Larice
+ * README.adms ,
+ * autogen.sh ,
+ * configure.ac ,
+ * configure.in ,
+ * src/frontend/cpitf.c ,
+ * src/misc/ivars.c :
+    rename configure.in -> configure.ac
+
 2010-09-08 Holger Vogt
  * visualc/include/config.h, vngspice.sln, vngspice.vcproj:
    prepare for ngspice22
diff --git a/README.adms b/README.adms
index d46f0f011..c7218009d 100644
--- a/README.adms
+++ b/README.adms
@@ -77,7 +77,7 @@ Limitations:
   Once you have found the (device_type, device_level) couple you have
   identified the files you have to edit:  
 
-    <ngspice-data-tree>/configure.in
+    <ngspice-data-tree>/configure.ac
      Here you have to add the entries in adms section for your new directory 
      and library. 
 
@@ -157,7 +157,7 @@ Limitations:
   06.01 Manual changes
     In directory <ngspice-data-tree> edit file configure.ac, add new device 'hicum0'
     (use the name of the directory - not the name of the module):
-      $ grep hicum0 configure.in
+      $ grep hicum0 configure.ac
       src/spicelib/devices/adms/hicum0/Makefile       \
     In directory <ngspice-data-tree>/src/spicelib/devices edit file Makefile.am, add new device 'hicum0':
       $ grep hicum0 Makefile.am
diff --git a/autogen.sh b/autogen.sh
index eb1ce4f77..1d99d6e32 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -7,9 +7,9 @@
 #
 # $Id$
 #
-# temp-adms.ac: modified configure.in if --adms is selected
+# temp-adms.ac: modified configure.ac if --adms is selected
 # for temporary use by autoconf, will be deleted automatically
-# configure.in stays untouched
+# configure.ac stays untouched
 
 PROJECT=ngspice
 TEST_TYPE=-f
@@ -146,19 +146,19 @@ check_awk
 #                 src\/spicelib\/devices\/adms\/mextram\/Makefile\
 #                 src\/spicelib\/devices\/adms\/psp102\/Makefile/g' configure.temp >configure.ac
   
-  # automake and autoconf need these entries in configure.in for adms enabled  
+  # automake and autoconf need these entries in configure.ac for adms enabled  
   z=""
   znew=""
   # Find all lines with "#VLAMKF" and put the second token of each line into shell variable z
   # as input to additional automake call for the adms directories
-  z=`cat configure.in | awk -v z=${z} '$1 ~ /#VLAMKF/{ z=$2; print "./"z }' `
+  z=`cat configure.ac | awk -v z=${z} '$1 ~ /#VLAMKF/{ z=$2; print "./"z }' `
   # same as above, sed requires \ at line endings, to be added to temp-adms.ac used by autoconf
-  znew=`cat configure.in | awk -v z=${znew} '$1 ~ /#VLAMKF/{ znew=$2; print "             "znew"\\\" }' `
+  znew=`cat configure.ac | awk -v z=${znew} '$1 ~ /#VLAMKF/{ znew=$2; print "             "znew"\\\" }' `
  
  # Find "tests/vbic/Makefile" and replace by tests/vbic/Makefile plus contents of variable z
   sed -e "
   s,tests\\/vbic\\/Makefile,tests\\/vbic\\/Makefile\\
-  $znew ," configure.in >temp-adms.ac
+  $znew ," configure.ac >temp-adms.ac
   
   currentdir=`pwd`
   
diff --git a/configure.in b/configure.ac
similarity index 99%
rename from configure.in
rename to configure.ac
index a267f9fc4..41a64b2e9 100644
--- a/configure.in
+++ b/configure.ac
@@ -1,4 +1,4 @@
-dnl configure.in script for ngspice
+dnl configure.ac script for ngspice
 dnl
 dnl This file is part of ngspice.
 dnl
diff --git a/src/frontend/cpitf.c b/src/frontend/cpitf.c
index b57c2bfe2..4e86de7c7 100644
--- a/src/frontend/cpitf.c
+++ b/src/frontend/cpitf.c
@@ -212,7 +212,7 @@ ft_cpinit(void)
     /* Reset this for the front end. */
     cp_hash = '*';
 
-    /* NGSPICEDATADIR has been set to path "$dprefix/share/ngspice" in configure.in, 
+    /* NGSPICEDATADIR has been set to path "$dprefix/share/ngspice" in configure.ac, 
        Spice_Lib_Dir has been set to NGSPICEDATADIR in conf.c, 
        may be overridden by environmental variable SPICE_LIB_DIR in ivars().
        Lib_Path has been set to Spice_Lib_Dir adding /scripts in ivars() */
diff --git a/src/misc/ivars.c b/src/misc/ivars.c
index 868ff5532..1efd08356 100644
--- a/src/misc/ivars.c
+++ b/src/misc/ivars.c
@@ -56,8 +56,8 @@ void
 ivars(void)
 {
     char *temp=NULL;
-	 /* $dprefix has been set to /usr/local or C:/Spice (Windows) in configure.in,
-    NGSPICEBINDIR has been set to $dprefix/bin in configure.in, 
+	 /* $dprefix has been set to /usr/local or C:/Spice (Windows) in configure.ac,
+    NGSPICEBINDIR has been set to $dprefix/bin in configure.ac, 
     Spice_Exec_Dir has been set to NGSPICEBINDIR in conf.c,
     may be overridden here by environmental variable SPICE_EXEC_DIR */
     env_overr(&Spice_Exec_Dir, "SPICE_EXEC_DIR");