diff --git a/.gitignore b/.gitignore
index 326971f..4ca21ed 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 CMakeFiles
-build
+build*/
 tests/CMakeFiles
 tests/Debug
 *.opensdf
diff --git a/include/gsl/pointers b/include/gsl/pointers
index 3a5409a..5e69f58 100644
--- a/include/gsl/pointers
+++ b/include/gsl/pointers
@@ -173,7 +173,7 @@ std::ostream& operator<<(std::ostream& os, const not_null<T>& val)
 #endif // !defined(GSL_NO_IOSTREAMS)
 
 template <class T, class U>
-auto operator==(const not_null<T>& lhs,
+constexpr auto operator==(const not_null<T>& lhs,
                 const not_null<U>& rhs) noexcept(noexcept(lhs.get() == rhs.get()))
     -> decltype(lhs.get() == rhs.get())
 {
@@ -181,7 +181,7 @@ auto operator==(const not_null<T>& lhs,
 }
 
 template <class T, class U>
-auto operator!=(const not_null<T>& lhs,
+constexpr auto operator!=(const not_null<T>& lhs,
                 const not_null<U>& rhs) noexcept(noexcept(lhs.get() != rhs.get()))
     -> decltype(lhs.get() != rhs.get())
 {
@@ -189,7 +189,7 @@ auto operator!=(const not_null<T>& lhs,
 }
 
 template <class T, class U>
-auto operator<(const not_null<T>& lhs,
+constexpr auto operator<(const not_null<T>& lhs,
                const not_null<U>& rhs) noexcept(noexcept(std::less<>{}(lhs.get(), rhs.get())))
     -> decltype(std::less<>{}(lhs.get(), rhs.get()))
 {
@@ -197,7 +197,7 @@ auto operator<(const not_null<T>& lhs,
 }
 
 template <class T, class U>
-auto operator<=(const not_null<T>& lhs,
+constexpr auto operator<=(const not_null<T>& lhs,
                 const not_null<U>& rhs) noexcept(noexcept(std::less_equal<>{}(lhs.get(), rhs.get())))
     -> decltype(std::less_equal<>{}(lhs.get(), rhs.get()))
 {
@@ -205,7 +205,7 @@ auto operator<=(const not_null<T>& lhs,
 }
 
 template <class T, class U>
-auto operator>(const not_null<T>& lhs,
+constexpr auto operator>(const not_null<T>& lhs,
                const not_null<U>& rhs) noexcept(noexcept(std::greater<>{}(lhs.get(), rhs.get())))
     -> decltype(std::greater<>{}(lhs.get(), rhs.get()))
 {
@@ -213,7 +213,7 @@ auto operator>(const not_null<T>& lhs,
 }
 
 template <class T, class U>
-auto operator>=(const not_null<T>& lhs,
+constexpr auto operator>=(const not_null<T>& lhs,
                 const not_null<U>& rhs) noexcept(noexcept(std::greater_equal<>{}(lhs.get(), rhs.get())))
     -> decltype(std::greater_equal<>{}(lhs.get(), rhs.get()))
 {
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 1f2bf7a..a8fd30a 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -204,6 +204,7 @@ add_executable(gsl_tests
     assertion_tests.cpp
     at_tests.cpp
     byte_tests.cpp
+    constexpr_notnull_tests.cpp
     notnull_tests.cpp
     owner_tests.cpp
     pointers_tests.cpp
diff --git a/tests/constexpr_notnull_tests.cpp b/tests/constexpr_notnull_tests.cpp
new file mode 100644
index 0000000..9192f85
--- /dev/null
+++ b/tests/constexpr_notnull_tests.cpp
@@ -0,0 +1,74 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2025 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <gsl/pointers> // for not_null
+#include <gtest/gtest.h>
+
+#include <type_traits> // for declval
+
+using namespace gsl;
+
+namespace
+{
+constexpr bool comparison_test(const int* ptr1, const int* ptr2)
+{
+    const not_null<const int*> p1(ptr1);
+    const not_null<const int*> p1_same(ptr1);
+    const not_null<const int*> p2(ptr2);
+    
+    // Testing operator==
+    const bool eq_result = (p1 == p1_same); // Should be true
+    const bool neq_result = (p1 != p2);     // Should be true
+    
+    // Testing operator<= and operator>=
+    const bool le_result = (p1 <= p1_same); // Should be true
+    const bool ge_result = (p1 >= p1_same); // Should be true
+    
+    // The exact comparison results will depend on pointer ordering,
+    // but we can verify that the basic equality checks work as expected
+    return eq_result && neq_result && le_result && ge_result;
+}
+
+constexpr bool workaround_test(const int* ptr1, const int* ptr2)
+{
+    const not_null<const int*> p1(ptr1);
+    const not_null<const int*> p1_same(ptr1);
+    const not_null<const int*> p2(ptr2);
+    
+    // Using .get() to compare
+    const bool eq_result = (p1.get() == p1_same.get()); // Should be true
+    const bool neq_result = (p1.get() != p2.get());     // Should be true
+    
+    return eq_result && neq_result;
+}
+} // namespace
+
+constexpr int test_value1 = 1;
+constexpr int test_value2 = 2;
+
+static_assert(comparison_test(&test_value1, &test_value2), "not_null comparison operators should be constexpr");
+static_assert(workaround_test(&test_value1, &test_value2), "not_null .get() comparison workaround should work");
+
+TEST(notnull_constexpr_tests, TestNotNullConstexprComparison)
+{
+    // This test simply verifies that the constexpr functions compile and run
+    // If we got here, it means the constexpr comparison operators are working
+    static const int value1 = 1;
+    static const int value2 = 2;
+    EXPECT_TRUE(comparison_test(&value1, &value2));
+    EXPECT_TRUE(workaround_test(&value1, &value2));
+}
+