diff --git a/.travis.yml b/.travis.yml
index cd53568..a037667 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,6 @@
 language: rust
+sudo: required
+cache: cargo
 rust:
   - stable
   - beta
@@ -16,4 +18,20 @@ matrix:
   allow_failures:
     - rust: nightly
   fast_finish: true
-cache: cargo
+addons:
+  apt:
+    packages:
+      - libcurl4-openssl-dev
+      - libelf-dev
+      - libdw-dev
+      - binutils-dev
+      - cmake
+    sources:
+      - kalakris-cmake
+
+cache:
+  directories:
+    - /home/travis/.cargo
+
+before_cache:
+  - rm -rf /home/travis/.cargo/registry
diff --git a/src/lib.rs b/src/lib.rs
index ba290e0..4385b23 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -44,6 +44,19 @@
 //!     assert_eq!("You are not allowed to do this", res);
 //! }
 //! ```
+//!
+//! If the key is missing, your code will not compile
+
+//! ```rust,compile_fail
+//! use internationalization::t;
+//!
+//! fn main() {
+//!     let lang = "en";
+//!     let res = t!("missing key", lang);
+
+//!     // Code will not compile
+//! }
+//! ```
 
 //! ## Installation
 
@@ -80,6 +93,15 @@ mod tests {
     #[test]
     fn it_translates() {
         assert_eq!(t!("key.test", "en"), "This is a test");
+        assert_eq!(t!("key.test", "fr"), "C'est un test");
+        assert_eq!(
+            t!("err.not_allowed", "fr"),
+            "Vous n'êtes pas autorisé à faire cela"
+        );
+        assert_eq!(
+            t!("err.not_allowed", "en"),
+            "You are not allowed to do this"
+        );
     }
     #[test]
     #[should_panic]