Solaris does not have vasnprintf()
diff --git a/configure.ac b/configure.ac
index adb5245..191d013 100644
--- a/configure.ac
+++ b/configure.ac
@@ -244,6 +244,7 @@
 AC_CHECK_FUNCS(mkstemps)
 AC_CHECK_FUNCS(timegm)
 AC_CHECK_DECLS(alloca strcasecmp)
+AC_CHECK_DECLS(vasprintf)
 AC_TRY_LINK_FUNC([symlink],[AC_DEFINE([HAVE_SYMLINK], 1, [Define to 1 if you have the symlink function.])])
 
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