diff --git a/scripts/build/mpfr.sh b/scripts/build/mpfr.sh
index 9519776c..d6cd6ab4 100644
--- a/scripts/build/mpfr.sh
+++ b/scripts/build/mpfr.sh
@@ -26,6 +26,17 @@ do_mpfr() {
 
     CT_DoStep INFO "Installing MPFR"
 
+    # OK, Gentoo have a sanity check that libtool.m4 and ltmain.sh have the
+    # same version number. Unfortunately, some tarballs of MPFR are not
+    # built sanely, and thus ./configure fails on Gentoo.
+    # See: http://sourceware.org/ml/crossgcc/2008-05/msg00080.html
+    # and: http://sourceware.org/ml/crossgcc/2008-06/msg00005.html
+    # This hack is not bad per se, but the MPFR guys would be better to not
+    # do that in the future...
+    CT_DoLog EXTRA "Re-building configuration files"
+    autoreconf -fi  2>&1 |CT_DoLog ALL
+    libtoolize      2>&1 |CT_DoLog ALL
+
     CT_DoLog EXTRA "Configuring MPFR"
     CFLAGS="${CT_CFLAGS_FOR_HOST}"                          \
     "${CT_SRC_DIR}/${CT_MPFR_FILE}/configure"               \