diff --git a/lib/url.c b/lib/url.c
index 13ce60a15..d65f6aec9 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -87,9 +87,18 @@
 #ifdef USE_LIBIDN
 #include <idna.h>
 #include <stringprep.h>
+#ifdef HAVE_IDN_FREE_H
+#include <idn-free.h>
+#else
 void idn_free (void *ptr); /* prototype from idn-free.h, not provided by
                               libidn 0.4.5's make install! */
 #endif
+#ifndef HAVE_IDN_FREE
+/* if idn_free() was not found in this version of libidn, use plain free()
+   instead */
+#define idn_free(x) (free)(x)
+#endif
+#endif
 
 #ifdef HAVE_OPENSSL_ENGINE_H
 #include <openssl/engine.h>