diff --git a/src/common/autoconfig.h.in b/src/common/autoconfig.h.in
index aaea24fd..123e528b 100644
--- a/src/common/autoconfig.h.in
+++ b/src/common/autoconfig.h.in
@@ -105,6 +105,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 
+/* Define to 1 if you have the `vsnprintf' function. */
+#undef HAVE_VSNPRINTF
+
 /* Define as const if the declaration of iconv() needs const. */
 #undef ICONV_CONST
 
diff --git a/src/configure.ac b/src/configure.ac
index 96d53871..a3ec86dc 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -37,7 +37,7 @@ AC_SYS_LARGEFILE
 # OpenBSD needs sys/param.h for mount.h to compile
 AC_CHECK_HEADERS([sys/param.h, spawn.h])
 
-AC_CHECK_FUNCS([posix_spawn setrlimit kqueue])
+AC_CHECK_FUNCS([posix_spawn setrlimit kqueue vsnprintf])
 
 if test "x$ac_cv_func_posix_spawn" = xyes; then :
    AC_ARG_ENABLE(posix_spawn,