diff --git a/src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.cs b/src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.cs
index a3e6a8947eb2c8..0199d29a73f34b 100644
--- a/src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.cs
+++ b/src/libraries/System.Numerics.Tensors/src/System/Buffers/NIndex.cs
@@ -175,7 +175,7 @@ public override string ToString()
         private string ToStringFromEnd()
         {
             Span<char> span = stackalloc char[21]; // 1 for ^ and 20 for longest possible nuint value
-            bool formatted = ((uint)Value).TryFormat(span.Slice(1), out int charsWritten);
+            bool formatted = ((nuint)Value).TryFormat(span.Slice(1), out int charsWritten);
             Debug.Assert(formatted);
             span[0] = '^';
             return new string(span.Slice(0, charsWritten + 1));
diff --git a/src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.cs b/src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.cs
index ad452f8385c4b8..2d713ba71fff4b 100644
--- a/src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.cs
+++ b/src/libraries/System.Numerics.Tensors/src/System/Buffers/NRange.cs
@@ -70,7 +70,7 @@ public override string ToString()
                 span[0] = '^';
                 pos = 1;
             }
-            bool formatted = ((uint)Start.Value).TryFormat(span.Slice(pos), out int charsWritten);
+            bool formatted = ((nuint)Start.Value).TryFormat(span.Slice(pos), out int charsWritten);
             Debug.Assert(formatted);
             pos += charsWritten;
 
@@ -81,7 +81,7 @@ public override string ToString()
             {
                 span[pos++] = '^';
             }
-            formatted = ((uint)End.Value).TryFormat(span.Slice(pos), out charsWritten);
+            formatted = ((nuint)End.Value).TryFormat(span.Slice(pos), out charsWritten);
             Debug.Assert(formatted);
             pos += charsWritten;
 
diff --git a/src/libraries/System.Numerics.Tensors/tests/NIndexTests.cs b/src/libraries/System.Numerics.Tensors/tests/NIndexTests.cs
index 193e6b33a1d530..72d41f94951e41 100644
--- a/src/libraries/System.Numerics.Tensors/tests/NIndexTests.cs
+++ b/src/libraries/System.Numerics.Tensors/tests/NIndexTests.cs
@@ -106,14 +106,28 @@ public static void HashCodeTest()
             Assert.NotEqual(index1.GetHashCode(), index2.GetHashCode());
         }
 
-        [Fact]
-        public static void ToStringTest()
+        [Theory]
+        [InlineData(0, false, "0")]
+        [InlineData(100, false, "100")]
+        [InlineData(0, true, "^0")]
+        [InlineData(50, true, "^50")]
+        [InlineData(int.MaxValue, false, "2147483647")]
+        [InlineData(int.MaxValue, true, "^2147483647")]
+        public static void ToStringTest(long value, bool fromEnd, string expected)
         {
-            NIndex index1 = 100;
-            Assert.Equal(100.ToString(), index1.ToString());
+            NIndex index = new NIndex((nint)value, fromEnd);
+            Assert.Equal(expected, index.ToString());
+        }
 
-            index1 = new NIndex(50, fromEnd: true);
-            Assert.Equal("^" + 50.ToString(), index1.ToString());
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]
+        [InlineData(1L + uint.MaxValue, false, "4294967296")]
+        [InlineData(1L + uint.MaxValue, true, "^4294967296")]
+        [InlineData(long.MaxValue, false, "9223372036854775807")]
+        [InlineData(long.MaxValue, true, "^9223372036854775807")]
+        public static void ToStringTest_64bit(long value, bool fromEnd, string expected)
+        {
+            NIndex index = new NIndex((nint)value, fromEnd);
+            Assert.Equal(expected, index.ToString());
         }
 
         [Fact]
diff --git a/src/libraries/System.Numerics.Tensors/tests/NRangeTests.cs b/src/libraries/System.Numerics.Tensors/tests/NRangeTests.cs
index eb5d7ba88ae45e..37231c6f1986d1 100644
--- a/src/libraries/System.Numerics.Tensors/tests/NRangeTests.cs
+++ b/src/libraries/System.Numerics.Tensors/tests/NRangeTests.cs
@@ -105,14 +105,26 @@ public static void HashCodeTest()
             Assert.NotEqual(NativeRange1.GetHashCode(), NativeRange2.GetHashCode());
         }
 
-        [Fact]
-        public static void ToStringTest()
+        [Theory]
+        [InlineData(10, false, 20, false, "10..20")]
+        [InlineData(10, false, 20, true, "10..^20")]
+        [InlineData(0, true, 0, true, "^0..^0")]
+        [InlineData(5, true, 10, false, "^5..10")]
+        [InlineData(int.MaxValue, false, int.MaxValue, true, "2147483647..^2147483647")]
+        public static void ToStringTest(long startValue, bool startFromEnd, long endValue, bool endFromEnd, string expected)
         {
-            NRange NativeRange1 = new NRange(new NIndex(10, fromEnd: false), new NIndex(20, fromEnd: false));
-            Assert.Equal(10.ToString() + ".." + 20.ToString(), NativeRange1.ToString());
+            NRange range = new NRange(new NIndex((nint)startValue, startFromEnd), new NIndex((nint)endValue, endFromEnd));
+            Assert.Equal(expected, range.ToString());
+        }
 
-            NativeRange1 = new NRange(new NIndex(10, fromEnd: false), new NIndex(20, fromEnd: true));
-            Assert.Equal(10.ToString() + "..^" + 20.ToString(), NativeRange1.ToString());
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.Is64BitProcess))]
+        [InlineData(1L + uint.MaxValue, false, 1L + uint.MaxValue, true, "4294967296..^4294967296")]
+        [InlineData(long.MaxValue, false, long.MaxValue, true, "9223372036854775807..^9223372036854775807")]
+        [InlineData(1L + uint.MaxValue, true, long.MaxValue, false, "^4294967296..9223372036854775807")]
+        public static void ToStringTest_64bit(long startValue, bool startFromEnd, long endValue, bool endFromEnd, string expected)
+        {
+            NRange range = new NRange(new NIndex((nint)startValue, startFromEnd), new NIndex((nint)endValue, endFromEnd));
+            Assert.Equal(expected, range.ToString());
         }
 
         [Fact]