diff --git a/README.install b/README.install
index f29c942da..27c3d63b5 100644
--- a/README.install
+++ b/README.install
@@ -172,10 +172,13 @@ optimized BLAS by Kazushige Goto.
 They can be downloaded freely (but not redistributed!) from:
 http://www.cs.utexas.edu/users/flame/goto/
 
-The FFTW library can also be replaced by vendor-specific FFT
-libraries, when available, or you can link to a precompiled FFTW
-library.  Please note that you must use FFTW version 2.  Support for
-version 3 is in progress: contact the developers if you want to try.
+At compilation time you have to choose whether to use the built-in
+copy of FFTW (v.<3), a precompiled FFTW v.<3 library, or a
+precompiled FFTW v.3 library. This is done using preprocessing
+options with rather obvious meaning : __FFTW, __USE_INTERNAL_FFTW, __FFTW3
+
+The FFTW library can also be replaced by vendor-specific FFT libraries, 
+when available.
 
 Finally, Quantum-ESPRESSO can use the MASS vector math library from
 IBM, if available (only on AIX).
@@ -203,14 +206,14 @@ specified value, and won't do any extra search.  This is so that if
 "configure" finds any library that you don't want to use, you can
 override it.
 
-If you want to use a precompiled FFTW library, the corresponding
-"fftw.h" include file is also required.  That may or may not have been
+If you want to use a precompiled FFTW v.<3 library, you will need 
+the corresponding "fftw.h" include file. That may or may not have been
 installed on your system together with the library: in particular,
 most Linux distributions split libraries into ``base'' and
 ``development'' packages, include files normally belonging to the
 latter.  Thus if you can't find "fftw.h" on your machine, chances are
-you must install the FFTW development package (how exactly it's called
-depends on your distribution).
+you must install the FFTW development package (how to do this and
+what it is exactly called depends on your operating system version).
 
 If instead the file is there, but "configure" doesn't find it, you may
 specify its location in the INCLUDEFFTW environment variable.
diff --git a/configure b/configure
index 490d18797..2dd14738e 100755
--- a/configure
+++ b/configure
@@ -3793,7 +3793,7 @@ alinux:fort )
 alpha:f90 )
 	have_cpp=1
 	pre_fdflags="-cpp "
-	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io"
+	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io -fpe1"
 	try_f90flags="\$(FFLAGS) -free"
 	try_fflags_noopt="-O0 -real_size 64 -align dcommons -align records -assume buffered_io"
 	try_f90flags_noopt="\$(FFLAGS_NOOPT) -free"
diff --git a/configure.ac b/configure.ac
index cd041b9c2..c734b57f9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -532,7 +532,7 @@ alinux:fort )
 alpha:f90 )
 	have_cpp=1
 	pre_fdflags="-cpp "
-	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io"
+	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io -fpe1"
 	try_f90flags="\$(FFLAGS) -free"
 	try_fflags_noopt="-O0 -real_size 64 -align dcommons -align records -assume buffered_io"
 	try_f90flags_noopt="\$(FFLAGS_NOOPT) -free"
diff --git a/install/configure b/install/configure
index 490d18797..2dd14738e 100755
--- a/install/configure
+++ b/install/configure
@@ -3793,7 +3793,7 @@ alinux:fort )
 alpha:f90 )
 	have_cpp=1
 	pre_fdflags="-cpp "
-	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io"
+	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io -fpe1"
 	try_f90flags="\$(FFLAGS) -free"
 	try_fflags_noopt="-O0 -real_size 64 -align dcommons -align records -assume buffered_io"
 	try_f90flags_noopt="\$(FFLAGS_NOOPT) -free"
diff --git a/install/configure.ac b/install/configure.ac
index cd041b9c2..c734b57f9 100644
--- a/install/configure.ac
+++ b/install/configure.ac
@@ -532,7 +532,7 @@ alinux:fort )
 alpha:f90 )
 	have_cpp=1
 	pre_fdflags="-cpp "
-	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io"
+	try_fflags="-O -real_size 64 -align dcommons -align records -assume buffered_io -fpe1"
 	try_f90flags="\$(FFLAGS) -free"
 	try_fflags_noopt="-O0 -real_size 64 -align dcommons -align records -assume buffered_io"
 	try_f90flags_noopt="\$(FFLAGS_NOOPT) -free"
diff --git a/release.sh b/release.sh
index f0a393282..6ebd87df7 100644
--- a/release.sh
+++ b/release.sh
@@ -1,6 +1,6 @@
 #!/bin/sh -x
 #
-VERSION=3.0
+VERSION=3.1
 TARGET_MACHINE=cibs.sns.it:public_html/public/
 #
 TMPDIR=espresso-$VERSION