diff --git a/configure b/configure
index 1ff0a44d3e..a6efd3552a 100755
--- a/configure
+++ b/configure
@@ -1850,7 +1850,7 @@ case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac
 
 
 test "x$prefix" = "xNONE" && prefix=$ac_default_prefix
-test "x$exec_prefix" = "xNONE" && exec_prefix=$ac_default_prefix
+test "x$exec_prefix" = "xNONE" && exec_prefix=${prefix}
 
 BINDIR=$prefix/bin
 
diff --git a/m4/paths.m4 b/m4/paths.m4
index 717fcd1356..eac50afe96 100644
--- a/m4/paths.m4
+++ b/m4/paths.m4
@@ -1,7 +1,7 @@
 AC_DEFUN([AX_XEN_EXPAND_CONFIG], [
 dnl expand these early so we can use this for substitutions
 test "x$prefix" = "xNONE" && prefix=$ac_default_prefix
-test "x$exec_prefix" = "xNONE" && exec_prefix=$ac_default_prefix
+test "x$exec_prefix" = "xNONE" && exec_prefix=${prefix}
 
 BINDIR=$prefix/bin
 AC_SUBST(BINDIR)
diff --git a/tools/configure b/tools/configure
index 7c9bbca8a1..3830da4ac7 100755
--- a/tools/configure
+++ b/tools/configure
@@ -3681,7 +3681,7 @@ esac
 
 
 test "x$prefix" = "xNONE" && prefix=$ac_default_prefix
-test "x$exec_prefix" = "xNONE" && exec_prefix=$ac_default_prefix
+test "x$exec_prefix" = "xNONE" && exec_prefix=${prefix}
 
 BINDIR=$prefix/bin