"Tried to use insecure HTTP repository without TLS"

```
lein repl
Tried to use insecure HTTP repository without TLS:
 Immutant incremental builds: http://downloads.immutant.org/incremental/
 org/jboss/naming/jnpserver/5.0.3.GA/jnpserver-5.0.3.GA.pom

This is almost certainly a mistake; for details see
https://github.com/technomancy/leiningen/blob/master/doc/FAQ.md
```

Does anyone know how this can be fixed?