diff --git a/configure.ac b/configure.ac
index 74946b0..618b566 100644
--- a/configure.ac
+++ b/configure.ac
@@ -13,7 +13,7 @@ AM_INIT_AUTOMAKE
 # Checks for programs.
 AC_PROG_CXX
 AC_LANG([C++])
-AC_PROG_CPP
+AC_REQUIRE_CPP
 AC_PROG_INSTALL
 AC_PROG_LN_S
 AC_PROG_MAKE_SET
diff --git a/doc/.gitignore b/doc/.gitignore
index ff6aa8f..e90722f 100644
--- a/doc/.gitignore
+++ b/doc/.gitignore
@@ -1,2 +1 @@
 /index.html
-/deploy/