diff --git a/CHANGELOG.md b/CHANGELOG.md
index 115567d0f..b8d330783 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 - Add ability to compare an EasyPost object to a parameter set object via `Matches` function
   - Users can define a custom `Matches` function on any parameter set class
-- Fix parameter set serialization that was causing GetNextPage functions to malfunction when iterating through more than two pages
+- Fix parameter set serialization that was causing issues when altering and reusing parameter sets
 
 ## v5.5.0 (2023-08-29)
 
diff --git a/EasyPost.Tests/ParametersTests/ParametersTest.cs b/EasyPost.Tests/ParametersTests/ParametersTest.cs
index 0f47c9282..8ee9ea065 100644
--- a/EasyPost.Tests/ParametersTests/ParametersTest.cs
+++ b/EasyPost.Tests/ParametersTests/ParametersTest.cs
@@ -108,6 +108,43 @@ public void TestParametersToDictionaryWithSubDictionary()
             Assert.Equal(streetB, addressData["street1"]);
         }
 
+        /// <summary>
+        ///     This test proves that you can reuse a parameter object, and that re-serializing it will take into account any changes made to its properties since the last serialization.
+        /// </summary>
+        [Fact]
+        [Testing.Logic]
+        public void TestReusingParameterSets()
+        {
+            var parameters = new Parameters.Shipment.All
+            {
+                BeforeId = null,
+            };
+
+            // null values should not be serialized
+            var parametersDictionary = parameters.ToDictionary();
+            Assert.False(parametersDictionary.ContainsKey("before_id"));
+
+            parameters.BeforeId = "1";
+
+            // now that the property has a value, it should be serialized
+            parametersDictionary = parameters.ToDictionary();
+            Assert.True(parametersDictionary.ContainsKey("before_id"));
+            Assert.Equal("1", parametersDictionary["before_id"]);
+
+            parameters.BeforeId = "2";
+
+            // the new value should be serialized
+            parametersDictionary = parameters.ToDictionary();
+            Assert.True(parametersDictionary.ContainsKey("before_id"));
+            Assert.Equal("2", parametersDictionary["before_id"]);
+
+            parameters.BeforeId = null;
+
+            // null values should not be serialized
+            parametersDictionary = parameters.ToDictionary();
+            Assert.False(parametersDictionary.ContainsKey("before_id"));
+        }
+
         [Fact]
         [Testing.Exception]
         public void TestRequiredAndOptionalParameterValidation()
diff --git a/EasyPost/Parameters/BaseParameters.cs b/EasyPost/Parameters/BaseParameters.cs
index 36892740b..a3e09b5d2 100644
--- a/EasyPost/Parameters/BaseParameters.cs
+++ b/EasyPost/Parameters/BaseParameters.cs
@@ -58,6 +58,8 @@ public virtual Dictionary<string, object> ToDictionary()
             // Bad stuff could happen if we allow end-users to convert a parameter object to a dictionary themselves and try to use it in the normal functions
             // In particular, a lot of the normal functions do additional wrapping of their dictionaries, which would result in invalid JSON schemas being sent to the API
 
+            _parameterDictionary = new Dictionary<string, object?>();
+
             // Construct the dictionary of all parameters
             PropertyInfo[] properties = GetType().GetProperties(BindingFlags.Instance |
                                                                 BindingFlags.NonPublic |
@@ -106,6 +108,8 @@ public virtual Dictionary<string, object> ToDictionary()
         /// <returns><see cref="Dictionary{TKey,TValue}" /> of parameters.</returns>
         public virtual Dictionary<string, object> ToSubDictionary(Type parentParameterObjectType)
         {
+            _parameterDictionary = new Dictionary<string, object?>();
+
             // Construct the dictionary of all parameters
             PropertyInfo[] properties = GetType().GetProperties(BindingFlags.Instance |
                                                                 BindingFlags.NonPublic |