diff --git a/urjtag/ChangeLog b/urjtag/ChangeLog
index 68347582..a11e4e80 100644
--- a/urjtag/ChangeLog
+++ b/urjtag/ChangeLog
@@ -1,3 +1,8 @@
+2011-06-24  Mike Frysinger  <vapier@gentoo.org>
+
+  * acinclude.m4: Add a new AS_VAR_PREPEND helper.
+  * configure.ac: Use AS_VAR_PREPEND rather than touching the var directly.
+
 2011-06-23  Mike Frysinger  <vapier@gentoo.org>
 
   * src/cmd/Makefile.am: Tweak dependencies so things work from a fresh
diff --git a/urjtag/acinclude.m4 b/urjtag/acinclude.m4
index 70889db2..59fcc23d 100644
--- a/urjtag/acinclude.m4
+++ b/urjtag/acinclude.m4
@@ -139,6 +139,16 @@ AC_DEFUN([AC_PROG_SED],
 ])dnl
 
 
+dnl AS_VAR_PREPEND
+dnl -------------
+dnl
+dnl this isn't in autoconf (yet?)
+dnl
+m4_ifndef([AS_VAR_PREPEND],[dnl
+AC_DEFUN([AS_VAR_PREPEND], [$1=$2${$1}])
+])dnl
+
+
 dnl AS_VAR_APPEND
 dnl -------------
 dnl
diff --git a/urjtag/configure.ac b/urjtag/configure.ac
index 52d5d4ca..90b167b9 100644
--- a/urjtag/configure.ac
+++ b/urjtag/configure.ac
@@ -344,7 +344,7 @@ AS_IF([test "x$enable_werror" = xyes], [
 ])
 AC_SUBST(WARNINGCFLAGS)
 
-CPPFLAGS="-I\$(top_srcdir) -I\$(top_srcdir)/include $CPPFLAGS"
+AS_VAR_PREPEND([CPPFLAGS], '-I$(top_srcdir) -I$(top_srcdir)/include ')
 
 AC_ARG_ENABLE([apps],
   [AS_HELP_STRING([--disable-apps],