diff --git a/.travis.yml b/.travis.yml
index c46a2c790..f1dcd036a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,7 @@ sudo: required
 dist: trusty
 matrix:
   include:
-    - rust: 1.37.0
+    - rust: 1.42.0
       env:
        - FEATURES='test docs'
        - RUSTFLAGS='-D warnings'
diff --git a/src/error.rs b/src/error.rs
index 79acdd8b3..090937561 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -33,6 +33,7 @@ impl ShapeError {
 ///
 /// This enumeration is not exhaustive. The representation of the enum
 /// is not guaranteed.
+#[non_exhaustive]
 #[derive(Copy, Clone, Debug)]
 pub enum ErrorKind {
     /// incompatible shape
@@ -47,8 +48,6 @@ pub enum ErrorKind {
     Unsupported,
     /// overflow when computing offset, length, etc.
     Overflow,
-    #[doc(hidden)]
-    __Incomplete,
 }
 
 #[inline(always)]
@@ -81,7 +80,6 @@ impl fmt::Display for ShapeError {
             ErrorKind::OutOfBounds => "out of bounds indexing",
             ErrorKind::Unsupported => "unsupported operation",
             ErrorKind::Overflow => "arithmetic overflow",
-            ErrorKind::__Incomplete => "this error variant is not in use",
         };
         write!(f, "ShapeError/{:?}: {}", self.kind(), description)
     }
diff --git a/src/lib.rs b/src/lib.rs
index 1b7590da1..55b5a5080 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -61,7 +61,7 @@
 //!     needs matching memory layout to be efficient (with some exceptions).
 //!   + Efficient floating point matrix multiplication even for very large
 //!     matrices; can optionally use BLAS to improve it further.
-//! - **Requires Rust 1.37 or later**
+//! - **Requires Rust 1.42 or later**
 //!
 //! ## Crate Feature Flags
 //!
diff --git a/src/slice.rs b/src/slice.rs
index 15765c61d..86a2b0b8f 100644
--- a/src/slice.rs
+++ b/src/slice.rs
@@ -110,18 +110,12 @@ copy_and_clone! {SliceOrIndex}
 impl SliceOrIndex {
     /// Returns `true` if `self` is a `Slice` value.
     pub fn is_slice(&self) -> bool {
-        match self {
-            SliceOrIndex::Slice { .. } => true,
-            _ => false,
-        }
+        matches!(self, SliceOrIndex::Slice { .. })
     }
 
     /// Returns `true` if `self` is an `Index` value.
     pub fn is_index(&self) -> bool {
-        match self {
-            SliceOrIndex::Index(_) => true,
-            _ => false,
-        }
+        matches!(self, SliceOrIndex::Index(_))
     }
 
     /// Returns a new `SliceOrIndex` with the given step size (multiplied with
diff --git a/src/stacking.rs b/src/stacking.rs
index 3e3b1afd8..3774aa083 100644
--- a/src/stacking.rs
+++ b/src/stacking.rs
@@ -165,7 +165,7 @@ where
     let mut res = Array::from_shape_vec(res_dim, v)?;
 
     res.axis_iter_mut(axis)
-        .zip(arrays.into_iter())
+        .zip(arrays.iter())
         .for_each(|(mut assign_view, array)| {
             assign_view.assign(&array);
         });