diff --git a/.travis.yml b/.travis.yml
index 4079096..753fcb2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,13 +8,13 @@ rust:
 matrix:
   include:
   - env: RUSTFMT
-    rust: 1.25.0  # `stable`: Locking down for consistent behavior
+    rust: 1.27.0  # `stable`: Locking down for consistent behavior
     install:
       - rustup component add rustfmt-preview
     script:
       - cargo fmt -- --write-mode=diff
   - env: RUSTFLAGS="-D warnings"
-    rust: 1.25.0  # `stable`: Locking down for consistent behavior
+    rust: 1.27.0  # `stable`: Locking down for consistent behavior
     install:
     script:
     - cargo check --tests --all-features
diff --git a/src/assert.rs b/src/assert.rs
index 945df8c..6824930 100644
--- a/src/assert.rs
+++ b/src/assert.rs
@@ -1,3 +1,5 @@
+//! `process::Output` assertions.
+
 use std::fmt;
 use std::process;
 use std::str;
@@ -400,21 +402,69 @@ where
     }
 }
 
-impl IntoOutputPredicate<predicates::ord::EqPredicate<&'static [u8]>> for &'static [u8] {
-    type Predicate = predicates::ord::EqPredicate<&'static [u8]>;
+// Keep `predicates` concrete Predicates out of our public API.
+/// Predicate used by `IntoOutputPredicate` for bytes
+#[derive(Debug)]
+pub struct BytesContentOutputPredicate(predicates::ord::EqPredicate<&'static [u8]>);
+
+impl BytesContentOutputPredicate {
+    pub(crate) fn new(value: &'static [u8]) -> Self {
+        let pred = predicates::ord::eq(value);
+        BytesContentOutputPredicate(pred)
+    }
+}
+
+impl predicates::Predicate<[u8]> for BytesContentOutputPredicate {
+    fn eval(&self, item: &[u8]) -> bool {
+        self.0.eval(item)
+    }
+}
+
+impl fmt::Display for BytesContentOutputPredicate {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl IntoOutputPredicate<BytesContentOutputPredicate> for &'static [u8] {
+    type Predicate = BytesContentOutputPredicate;
 
     fn into_output(self) -> Self::Predicate {
-        predicates::ord::eq(self)
+        Self::Predicate::new(self)
     }
 }
 
-impl IntoOutputPredicate<predicates::str::Utf8Predicate<predicates::str::DifferencePredicate>>
-    for &'static str
-{
-    type Predicate = predicates::str::Utf8Predicate<predicates::str::DifferencePredicate>;
+// Keep `predicates` concrete Predicates out of our public API.
+/// Predicate used by `IntoOutputPredicate` for `str`
+#[derive(Debug, Clone)]
+pub struct StrContentOutputPredicate(
+    predicates::str::Utf8Predicate<predicates::str::DifferencePredicate>,
+);
+
+impl StrContentOutputPredicate {
+    pub(crate) fn new(value: &'static str) -> Self {
+        let pred = predicates::str::similar(value).from_utf8();
+        StrContentOutputPredicate(pred)
+    }
+}
+
+impl predicates::Predicate<[u8]> for StrContentOutputPredicate {
+    fn eval(&self, item: &[u8]) -> bool {
+        self.0.eval(item)
+    }
+}
+
+impl fmt::Display for StrContentOutputPredicate {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl IntoOutputPredicate<StrContentOutputPredicate> for &'static str {
+    type Predicate = StrContentOutputPredicate;
 
     fn into_output(self) -> Self::Predicate {
-        predicates::str::similar(self).from_utf8()
+        Self::Predicate::new(self)
     }
 }
 
diff --git a/src/cargo.rs b/src/cargo.rs
index 4a591bd..0f03fbf 100644
--- a/src/cargo.rs
+++ b/src/cargo.rs
@@ -107,7 +107,8 @@ struct MessageFilter<'a> {
 
 fn extract_filenames(msg: &escargot::Message, kind: &str) -> Option<path::PathBuf> {
     let filter: MessageFilter = msg.convert().ok()?;
-    if filter.reason != "compiler-artifact" || filter.target.crate_types != ["bin"]
+    if filter.reason != "compiler-artifact"
+        || filter.target.crate_types != ["bin"]
         || filter.target.kind != [kind]
     {
         None
diff --git a/src/lib.rs b/src/lib.rs
index df2fa92..cb32ea3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -45,8 +45,9 @@ extern crate predicates;
 #[macro_use]
 extern crate serde;
 
-mod assert;
-pub use assert::*;
+pub mod assert;
+pub use assert::Assert;
+pub use assert::OutputAssertExt;
 pub mod cargo;
 mod cmd;
 pub use cmd::*;
diff --git a/src/stdin.rs b/src/stdin.rs
index fe88403..ed00735 100644
--- a/src/stdin.rs
+++ b/src/stdin.rs
@@ -4,8 +4,8 @@ use std::process;
 
 use assert::Assert;
 use assert::OutputAssertExt;
-use cmd::OutputOkExt;
 use cmd::dump_buffer;
+use cmd::OutputOkExt;
 use errors::OutputError;
 use errors::OutputResult;