+#ifdef FEATURE_EXTERNAL_FILTERS
+extern privoxy_mutex_t external_filter_mutex;
+#endif
+
+#ifdef FEATURE_CLIENT_TAGS
+extern privoxy_mutex_t client_tags_mutex;
+#endif
+
+#ifndef HAVE_GMTIME_R
+extern privoxy_mutex_t gmtime_mutex;
+#endif /* ndef HAVE_GMTIME_R */
+
+#ifndef HAVE_LOCALTIME_R
+extern privoxy_mutex_t localtime_mutex;
+#endif /* ndef HAVE_GMTIME_R */
+
+#if !defined(HAVE_GETHOSTBYADDR_R) || !defined(HAVE_GETHOSTBYNAME_R)
+extern privoxy_mutex_t resolver_mutex;
+#endif /* !defined(HAVE_GETHOSTBYADDR_R) || !defined(HAVE_GETHOSTBYNAME_R) */
+
+#ifndef HAVE_RANDOM
+extern privoxy_mutex_t rand_mutex;
+#endif /* ndef HAVE_RANDOM */
+
+#ifdef FEATURE_HTTPS_INSPECTION
+extern privoxy_mutex_t certificate_mutex;
+extern privoxy_mutex_t rng_mutex;
+#endif
+
+#endif /* FEATURE_PTHREAD */