We don't build on stable... yet.

.travis.yml

@@ -3,6 +3,9 @@ rust:
   - stable
   - beta
   - nightly
+matrix:
+  allow_failures:
+    - rust: stable # until 1.15 comes out
 notifications:
   irc:
     channels:

README.md

@@ -7,7 +7,7 @@ include complicated compile-time computations, such as macro or type tricks, eve
 at cost of performance degradation.
 
 _smoltcp_ does not need heap allocation *at all*, is [extensively documented][docs],
-and compiles on stable Rust.
+and compiles on stable Rust 1.15 and later.
 
 [docs]: https://docs.rs/smoltcp/