diff --git a/stl/inc/complex b/stl/inc/complex
index e0aff1ed4ee..5e935cf52d0 100644
--- a/stl/inc/complex
+++ b/stl/inc/complex
@@ -1514,12 +1514,15 @@ _NODISCARD constexpr bool operator==(const complex<_Ty>& _Left, const _Ty& _Righ
     return _Left.real() == _Right && _Left.imag() == 0;
 }
 
+#if !_HAS_CXX20
 template <class _Ty>
 _NODISCARD constexpr bool operator==(const _Ty& _Left, const complex<_Ty>& _Right) {
     return _Left == _Right.real() && 0 == _Right.imag();
 }
+#endif // !_HAS_CXX20
 
 // FUNCTION TEMPLATE operator!=
+#if !_HAS_CXX20
 template <class _Ty>
 _NODISCARD constexpr bool operator!=(const complex<_Ty>& _Left, const complex<_Ty>& _Right) {
     return !(_Left == _Right);
@@ -1534,6 +1537,7 @@ template <class _Ty>
 _NODISCARD constexpr bool operator!=(const _Ty& _Left, const complex<_Ty>& _Right) {
     return !(_Left == _Right);
 }
+#endif // !_HAS_CXX20
 
 // FUNCTION TEMPLATE imag
 template <class _Ty>
diff --git a/stl/inc/valarray b/stl/inc/valarray
index 63b69f34fa4..5f5a6ab33fc 100644
--- a/stl/inc/valarray
+++ b/stl/inc/valarray
@@ -1373,6 +1373,12 @@ public:
         return _Stride;
     }
 
+#if _HAS_CXX20
+    _NODISCARD friend bool operator==(const slice& _Left, const slice& _Right) noexcept /* strengthened */ {
+        return _Left.start() == _Right.start() && _Left.size() == _Right.size() && _Left.stride() == _Right.stride();
+    }
+#endif // _HAS_CXX20
+
 protected:
     size_t _Start  = 0; // the starting offset
     size_t _Len    = 0; // the number of elements
diff --git a/tests/std/tests/P1614R2_spaceship/test.cpp b/tests/std/tests/P1614R2_spaceship/test.cpp
index c488238b56f..1775d4b97f3 100644
--- a/tests/std/tests/P1614R2_spaceship/test.cpp
+++ b/tests/std/tests/P1614R2_spaceship/test.cpp
@@ -27,6 +27,7 @@
 #include <unordered_map>
 #include <unordered_set>
 #include <utility>
+#include <valarray>
 #include <vector>
 
 template <class T>
@@ -483,6 +484,17 @@ void ordering_test_cases() {
 
         spaceship_test<std::strong_ordering>(c_mem[0], c_mem[0], c_mem[1]);
     }
+    { // slice
+        std::slice a1(2, 3, 4);
+        std::slice a2(2, 3, 4);
+        std::slice a3(3, 3, 4);
+        std::slice a4(2, 4, 4);
+        std::slice a5(2, 3, 3);
+        assert(a1 == a2);
+        assert(a1 != a3);
+        assert(a1 != a4);
+        assert(a1 != a5);
+    }
     { // filesystem::space_info
         constexpr std::filesystem::space_info si1{4'000'000'000'000, 2'000'000'000'000, 1'000'000'000'000};
         constexpr std::filesystem::space_info si2{4'000'000'000'000, 2'000'000'000'000, 1'000'000'000'000};