diff --git a/configure.ac b/configure.ac
index 0922e777..ad07a7e1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,6 +30,7 @@ AC_CONFIG_HEADERS([config.h])
 AM_INIT_AUTOMAKE([1.11.1 silent-rules foreign -Wall -Werror])
 
 # Checks for programs.
+AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_CC
 AC_PROG_INSTALL
 AC_PROG_RANLIB
@@ -38,6 +39,9 @@ AC_CHECK_PROG([AR], [ar], [ar], [ar])
 # Perl is needed for the test suite (only)
 AC_CHECK_PROG([PERL], [perl], [perl], [perl])
 
+# Needed for w32/Makefile.am
+AM_PROG_AR
+
 # Specialized system macros
 AC_CANONICAL_HOST
 AC_AIX