diff --git a/src/libraries/System.Collections.Immutable/src/System/Collections/Frozen/String/LengthBuckets.cs b/src/libraries/System.Collections.Immutable/src/System/Collections/Frozen/String/LengthBuckets.cs
index 626b21a8bf1212..ac2f17bca8372e 100644
--- a/src/libraries/System.Collections.Immutable/src/System/Collections/Frozen/String/LengthBuckets.cs
+++ b/src/libraries/System.Collections.Immutable/src/System/Collections/Frozen/String/LengthBuckets.cs
@@ -27,11 +27,11 @@ internal static class LengthBuckets
                 return null;
             }
 
-            int arraySize = spread * MaxPerLength;
+            long expectedArraySize = (long)spread * MaxPerLength;
 #if NET
-            if (arraySize > Array.MaxLength)
+            if (expectedArraySize > Array.MaxLength)
 #else
-            if (arraySize > 0X7FFFFFC7)
+            if (expectedArraySize > 0X7FFFFFC7)
 #endif
             {
                 // In the future we may lower the value, as it may be quite unlikely
@@ -39,6 +39,8 @@ internal static class LengthBuckets
                 return null;
             }
 
+            int arraySize = (int)expectedArraySize;
+
             // Instead of creating a dictionary of lists or a multi-dimensional array
             // we rent a single dimension array, where every bucket has five slots.
             // The bucket starts at (key.Length - minLength) * 5.
diff --git a/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenDictionaryTests.cs b/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenDictionaryTests.cs
index 61b2bea331f857..14c967ce573098 100644
--- a/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenDictionaryTests.cs
+++ b/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenDictionaryTests.cs
@@ -419,6 +419,19 @@ public void ContainsKey_WithNonAscii(int percentageWithNonAscii)
 
             Assert.All(expected, kvp => actual.ContainsKey(kvp.Key));
         }
+
+        [Fact]
+        [OuterLoop]
+        public void ToFrozenDictionary_WithExtremelyLargeStrings()
+        {
+            // Test case with extremely large strings that exceed length bucket boundaries.
+            var keys = new[] { "", new string('a', 0X7FFFFFC7 / 4) };
+            var frozen = keys.ToFrozenDictionary(s => s, GetKeyIEqualityComparer());
+            Assert.Equal(keys.Length, frozen.Count);
+            Assert.Equal(keys.Length, frozen.Keys.Length);
+            Assert.Equal(keys.Length, frozen.Values.Length);
+            Assert.All(keys, key => frozen.ContainsKey(key));
+        }
     }
 
     public class FrozenDictionary_Generic_Tests_string_string_Default : FrozenDictionary_Generic_Tests_string_string
diff --git a/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenSetTests.cs b/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenSetTests.cs
index 989292fe7b4f2d..a021dc2353b285 100644
--- a/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenSetTests.cs
+++ b/src/libraries/System.Collections.Immutable/tests/Frozen/FrozenSetTests.cs
@@ -376,6 +376,17 @@ public void Contains_WithNonAscii(int percentageWithNonAscii)
 
             Assert.All(expected, s => actual.Contains(s));
         }
+
+        [Fact]
+        [OuterLoop]
+        public void ToFrozenSet_WithExtremelyLargeStrings()
+        {
+            // Test case with extremely large strings that exceed length bucket boundaries.
+            var keys = new[] { "", new string('a', 0X7FFFFFC7 / 4) };
+            var frozen = keys.ToFrozenSet(GetIEqualityComparer());
+            Assert.Equal(keys.Length, frozen.Count);
+            Assert.All(keys, key => frozen.Contains(key));
+        }
     }
 
     public class FrozenSet_Generic_Tests_string_Default : FrozenSet_Generic_Tests_string