diff --git a/emacs.changes b/emacs.changes
index b7ad93c..25e4a9c 100644
--- a/emacs.changes
+++ b/emacs.changes
@@ -1,3 +1,10 @@
+-------------------------------------------------------------------
+Tue Mar 27 16:34:37 UTC 2018 - dimstar@opensuse.org
+
+- Explicitly call autoreconf, unless without autoconf is specified.
+  In this case, there is spec-file logic to touch timestampes of
+  relevant files. Move this logic to build instead of prep phase.
+
 -------------------------------------------------------------------
 Wed Mar 14 21:08:52 UTC 2018 - crrodriguez@opensuse.org
 
diff --git a/emacs.spec b/emacs.spec
index 23d0b4f..8364f06 100644
--- a/emacs.spec
+++ b/emacs.spec
@@ -270,6 +270,7 @@ and most assembler-like syntaxes.
 %patch27 -p0
 %patch   -p0 -b .0
 
+%build
 %if %{without autoconf}
 # We don't want to run autoconf
 if test configure.ac -nt aclocal.m4 -o m4/gnulib-comp.m4 -nt aclocal.m4 ; then
@@ -292,9 +293,10 @@ if test -s autogen.sh ; then
     mv autogen.sh autogen.sh.no
     ln -sf /bin/true autogen.sh
 fi
+%else
+autoreconf -fiv
 %endif
 
-%build
 # make sure that the binaries work (pagesize on build must be the same as on target, bnc#726769)
 %if %suse_version >= 1110
 %ifarch ppc ppc64 ia64