diff --git a/configure b/configure
index e23bc3663..d9e036b7c 100755
--- a/configure
+++ b/configure
@@ -4665,7 +4665,7 @@ fi
 if test "${enable_clpbn_bp+set}" = set; then :
   enableval=$enable_clpbn_bp; yap_cv_clpbn_bp="$enableval"
 else
-  yap_cv_clpbn_bp=no
+  yap_cv_clpbn_bp=yes
 fi
 
 
@@ -5084,10 +5084,10 @@ _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
-    yap_cv_clpbn_bp=yes
 else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
+    yap_cv_clpbn_bp=no
 
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
diff --git a/configure.in b/configure.in
index fc5f3ab86..e7ecdf500 100755
--- a/configure.in
+++ b/configure.in
@@ -218,7 +218,7 @@ AC_ARG_ENABLE(cplint,
 
 AC_ARG_ENABLE(clpbn-bp,
 	[ --enable-clpbn-bp           enable belief propagation solver in CLPBN.  ],
-	yap_cv_clpbn_bp="$enableval", yap_cv_clpbn_bp=no)
+	yap_cv_clpbn_bp="$enableval", yap_cv_clpbn_bp=yes)
 
 AC_ARG_WITH(gmp,
 	[ --with-gmp[=DIR]           use GNU Multiple Precision in DIR],
@@ -522,9 +522,9 @@ if test "$yap_cv_clpbn_bp"="yes"; then
   CXXFLAGS=-std=c++0x
   AC_MSG_CHECKING([whether CXX supports -std-c++0x])
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])],
-    [AC_MSG_RESULT([yes])]
-    [yap_cv_clpbn_bp=yes],
+    [AC_MSG_RESULT([yes])],
     [AC_MSG_RESULT([no])]
+    [yap_cv_clpbn_bp=no]
   )
   CXXFLAGS="$my_save_cxxflags"
   AC_LANG_POP()