transport: cast away constness for free
diff --git a/src/transports/smart.c b/src/transports/smart.c
index 11b4b09..7a35c39 100644
--- a/src/transports/smart.c
+++ b/src/transports/smart.c
@@ -444,7 +444,7 @@ static void git_smart__free(git_transport *transport)
git_pkt_free(p);
git_vector_free(refs);
- git__free(t->proxy.url);
+ git__free((char *)t->proxy.url);
git_strarray_free(&t->custom_headers);