diff --git a/.travis.yml b/.travis.yml
index b08828f..14e0e35 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -78,19 +78,7 @@ matrix:
 
     # Historical Rust versions
     - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.21.0
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.22.0
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.23.0
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.24.0
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.25.0
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.26.0
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.27.0
+      rust: 1.28.0
 
     # WASM support
     - env: TARGET=asmjs-unknown-emscripten USE_CARGO_WEB=true
diff --git a/README.md b/README.md
index 7d0762d..771ba1a 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,7 @@ Further examples can be found in the [examples](examples) directory on internati
 
 # Usage
 
-`dtparse` requires a minimum Rust version of 1.21 to build, but is tested on Windows, OSX,
+`dtparse` requires a minimum Rust version of 1.28 to build, but is tested on Windows, OSX,
 BSD, Linux, and WASM. The build is also compiled against the iOS and Android SDK's, but is not
 tested against them.
 
diff --git a/src/lib.rs b/src/lib.rs
index 04e84e2..3e8af54 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -63,7 +63,7 @@
 //!
 //! # Usage
 //!
-//! `dtparse` requires a minimum Rust version of 1.21 to build, but is tested on Windows, OSX,
+//! `dtparse` requires a minimum Rust version of 1.28 to build, but is tested on Windows, OSX,
 //! BSD, Linux, and WASM. The build is also compiled against the iOS and Android SDK's, but is not
 //! tested against them.
 //!
diff --git a/src/tests/tz.rs b/src/tests/tz.rs
index 8e866f3..f71f1ee 100644
--- a/src/tests/tz.rs
+++ b/src/tests/tz.rs
@@ -1,4 +1,4 @@
-use crate::parse;
+use parse;
 
 #[test]
 fn est() {