diff --git a/include/gsl/span b/include/gsl/span
index 76f16e1..04cf1af 100644
--- a/include/gsl/span
+++ b/include/gsl/span
@@ -199,7 +199,7 @@ namespace details
 
         constexpr span_iterator& operator-=(difference_type n) GSL_NOEXCEPT { return *this += -n; }
 
-        constexpr difference_type operator-(const span_iterator& rhs) const GSL_NOEXCEPT
+        constexpr difference_type operator-(span_iterator rhs) const GSL_NOEXCEPT
         {
             Expects(span_ == rhs.span_);
             return index_ - rhs.index_;
@@ -210,39 +210,39 @@ namespace details
             return *(*this + n);
         }
 
-        constexpr friend bool operator==(const span_iterator& lhs,
-                                         const span_iterator& rhs) GSL_NOEXCEPT
+        constexpr friend bool operator==(span_iterator lhs,
+                                         span_iterator rhs) GSL_NOEXCEPT
         {
             return lhs.span_ == rhs.span_ && lhs.index_ == rhs.index_;
         }
 
-        constexpr friend bool operator!=(const span_iterator& lhs,
-                                         const span_iterator& rhs) GSL_NOEXCEPT
+        constexpr friend bool operator!=(span_iterator lhs,
+                                         span_iterator rhs) GSL_NOEXCEPT
         {
             return !(lhs == rhs);
         }
 
-        constexpr friend bool operator<(const span_iterator& lhs,
-                                        const span_iterator& rhs) GSL_NOEXCEPT
+        constexpr friend bool operator<(span_iterator lhs,
+                                        span_iterator rhs) GSL_NOEXCEPT
         {
             Expects(lhs.span_ == rhs.span_);
             return lhs.index_ < rhs.index_;
         }
 
-        constexpr friend bool operator<=(const span_iterator& lhs,
-                                         const span_iterator& rhs) GSL_NOEXCEPT
+        constexpr friend bool operator<=(span_iterator lhs,
+                                         span_iterator rhs) GSL_NOEXCEPT
         {
             return !(rhs < lhs);
         }
 
-        constexpr friend bool operator>(const span_iterator& lhs,
-                                        const span_iterator& rhs) GSL_NOEXCEPT
+        constexpr friend bool operator>(span_iterator lhs,
+                                        span_iterator rhs) GSL_NOEXCEPT
         {
             return rhs < lhs;
         }
 
-        constexpr friend bool operator>=(const span_iterator& lhs,
-                                         const span_iterator& rhs) GSL_NOEXCEPT
+        constexpr friend bool operator>=(span_iterator lhs,
+                                         span_iterator rhs) GSL_NOEXCEPT
         {
             return !(rhs > lhs);
         }
@@ -255,7 +255,7 @@ namespace details
     template <class Span, bool IsConst>
     inline constexpr span_iterator<Span, IsConst>
     operator+(typename span_iterator<Span, IsConst>::difference_type n,
-              const span_iterator<Span, IsConst>& rhs) GSL_NOEXCEPT
+              span_iterator<Span, IsConst> rhs) GSL_NOEXCEPT
     {
         return rhs + n;
     }
@@ -263,7 +263,7 @@ namespace details
     template <class Span, bool IsConst>
     inline constexpr span_iterator<Span, IsConst>
     operator-(typename span_iterator<Span, IsConst>::difference_type n,
-              const span_iterator<Span, IsConst>& rhs) GSL_NOEXCEPT
+              span_iterator<Span, IsConst> rhs) GSL_NOEXCEPT
     {
         return rhs - n;
     }
@@ -535,43 +535,43 @@ private:
 
 // [span.comparison], span comparison operators
 template <class ElementType, std::ptrdiff_t FirstExtent, std::ptrdiff_t SecondExtent>
-inline constexpr bool operator==(const span<ElementType, FirstExtent>& l,
-                                 const span<ElementType, SecondExtent>& r)
+inline constexpr bool operator==(span<ElementType, FirstExtent> l,
+                                 span<ElementType, SecondExtent> r)
 {
     return std::equal(l.begin(), l.end(), r.begin(), r.end());
 }
 
 template <class ElementType, std::ptrdiff_t Extent>
-inline constexpr bool operator!=(const span<ElementType, Extent>& l,
-                                 const span<ElementType, Extent>& r)
+inline constexpr bool operator!=(span<ElementType, Extent> l,
+                                 span<ElementType, Extent> r)
 {
     return !(l == r);
 }
 
 template <class ElementType, std::ptrdiff_t Extent>
-inline constexpr bool operator<(const span<ElementType, Extent>& l,
-                                const span<ElementType, Extent>& r)
+inline constexpr bool operator<(span<ElementType, Extent> l,
+                                span<ElementType, Extent> r)
 {
     return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
 }
 
 template <class ElementType, std::ptrdiff_t Extent>
-inline constexpr bool operator<=(const span<ElementType, Extent>& l,
-                                 const span<ElementType, Extent>& r)
+inline constexpr bool operator<=(span<ElementType, Extent> l,
+                                 span<ElementType, Extent> r)
 {
     return !(l > r);
 }
 
 template <class ElementType, std::ptrdiff_t Extent>
-inline constexpr bool operator>(const span<ElementType, Extent>& l,
-                                const span<ElementType, Extent>& r)
+inline constexpr bool operator>(span<ElementType, Extent> l,
+                                span<ElementType, Extent> r)
 {
     return r < l;
 }
 
 template <class ElementType, std::ptrdiff_t Extent>
-inline constexpr bool operator>=(const span<ElementType, Extent>& l,
-                                 const span<ElementType, Extent>& r)
+inline constexpr bool operator>=(span<ElementType, Extent> l,
+                                 span<ElementType, Extent> r)
 {
     return !(l < r);
 }
@@ -662,7 +662,7 @@ span<typename Ptr::element_type> make_span(Ptr& cont)
 
 // Specialization of gsl::at for span
 template <class ElementType, std::ptrdiff_t Extent>
-inline constexpr ElementType& at(const span<ElementType, Extent>& s, std::ptrdiff_t index)
+inline constexpr ElementType& at(span<ElementType, Extent> s, std::ptrdiff_t index)
 {
     // No bounds checking here because it is done in span::operator[] called below
     return s[index];