diff --git a/RELEASE.md b/RELEASE.md
index df6dd929aecc73ddaabaa3ddd435dd7dcaa8081f..58c4bab707a2170dcee2a9b0ceeef6c9916dc4f6 100644
--- a/RELEASE.md
+++ b/RELEASE.md
@@ -5,18 +5,18 @@ Upstream
 
         export VERSION=x.y.z
 
-* update `configure.in` and `ChangeLog`
+* update `configure.ac` and `ChangeLog`
 
         perl -pi -E \
            "s{^AC_INIT\(\[backupninja\],\[[0-9.]+\],}{AC_INIT([backupninja],[$VERSION],}" \
-           configure.in && \
+           configure.ac && \
         RELEASE_DATE=$(LC_ALL=C date '+%B %d, %Y') perl -pi -E \
            "s{^version\s+[0-9.]+\s+--\s+UNRELEASED$}{version $VERSION -- $RELEASE_DATE}" \
            ChangeLog
 
 * commit, tag and create the tarball:
 
-        git commit configure.in ChangeLog \
+        git commit configure.ac ChangeLog \
             -m "Releasing backupninja $VERSION" && \
         git clean -fdx && \
         git tag -s "backupninja-$VERSION" \
diff --git a/autogen.sh b/autogen.sh
index aae1061bbd085d871930c8503040dc5d784b41e8..bb16216bad729ca85d1054cf31e37efda9e401c2 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -8,10 +8,10 @@ fi
 if [ "x$1" = "x-f"  ]
 then
     autoscan
-    [ -f "configure.in" ] && cp "configure.in" "configure.in.old"
-    mv -f "configure.scan" "configure.in"
-    echo "## This is just AUTOSCAN draft of configure.in"
-    $EDITOR "configure.in"
+    [ -f "configure.ac" ] && cp "configure.ac" "configure.ac.old"
+    mv -f "configure.scan" "configure.ac"
+    echo "## This is just AUTOSCAN draft of configure.ac"
+    $EDITOR "configure.ac"
 fi
 
 ### použít jen když je třeba použít configure.h.in