diff --git a/Funcky.DiscriminatedUnion.SourceGeneration/Emitter.cs b/Funcky.DiscriminatedUnion.SourceGeneration/Emitter.cs
index 4392e88..b457a8a 100644
--- a/Funcky.DiscriminatedUnion.SourceGeneration/Emitter.cs
+++ b/Funcky.DiscriminatedUnion.SourceGeneration/Emitter.cs
@@ -69,7 +69,7 @@ private static void WriteTupleReturningPartitionExtension(DiscriminatedUnion dis
         var namedResultPartitions = discriminatedUnion
             .Variants
             .JoinToInterpolation(
-                v => $"global::System.Collections.Generic.IReadOnlyList<{discriminatedUnion.Type.Identifier}.{v.LocalTypeName}> {v.ParameterName}",
+                v => $"global::System.Collections.Generic.IReadOnlyList<{discriminatedUnion.Type.Identifier}.{v.LocalTypeName}> {v.ParameterName[..1].ToUpper()}{v.ParameterName[1..]}",
                 ", ");
 
         writer.WriteLineInterpolated($"public static ({namedResultPartitions}) Partition(this global::System.Collections.Generic.IEnumerable<{discriminatedUnion.Type.Identifier}> source)");
diff --git a/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedNestedUnionWithPartition.01.verified.cs b/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedNestedUnionWithPartition.01.verified.cs
index 958c82b..9c3bf92 100644
--- a/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedNestedUnionWithPartition.01.verified.cs
+++ b/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedNestedUnionWithPartition.01.verified.cs
@@ -40,7 +40,7 @@ partial record Integer
     [global::System.CodeDom.Compiler.GeneratedCode("Funcky.DiscriminatedUnion.SourceGeneration", "1.2.0.0")]
     public static partial class FlattenedNestedUnionWithPartitionEnumerableExtensions
     {
-        public static (global::System.Collections.Generic.IReadOnlyList<FlattenedNestedUnionWithPartition.Keyword> keyword, global::System.Collections.Generic.IReadOnlyList<FlattenedNestedUnionWithPartition.Literal.Number.Integer> integer) Partition(this global::System.Collections.Generic.IEnumerable<FlattenedNestedUnionWithPartition> source)
+        public static (global::System.Collections.Generic.IReadOnlyList<FlattenedNestedUnionWithPartition.Keyword> Keyword, global::System.Collections.Generic.IReadOnlyList<FlattenedNestedUnionWithPartition.Literal.Number.Integer> Integer) Partition(this global::System.Collections.Generic.IEnumerable<FlattenedNestedUnionWithPartition> source)
         {
             var keywordItems = new global::System.Collections.Generic.List<FlattenedNestedUnionWithPartition.Keyword>();
             var integerItems = new global::System.Collections.Generic.List<FlattenedNestedUnionWithPartition.Literal.Number.Integer>();
diff --git a/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedUnionWithPartition.01.verified.cs b/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedUnionWithPartition.01.verified.cs
index d3389f9..6bc51e7 100644
--- a/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedUnionWithPartition.01.verified.cs
+++ b/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=FlattenedUnionWithPartition.01.verified.cs
@@ -34,7 +34,7 @@ partial record Integer
     [global::System.CodeDom.Compiler.GeneratedCode("Funcky.DiscriminatedUnion.SourceGeneration", "1.2.0.0")]
     public static partial class FlattenedUnionWithPartitionEnumerableExtensions
     {
-        public static (global::System.Collections.Generic.IReadOnlyList<FlattenedUnionWithPartition.Keyword> keyword, global::System.Collections.Generic.IReadOnlyList<FlattenedUnionWithPartition.Integer> integer) Partition(this global::System.Collections.Generic.IEnumerable<FlattenedUnionWithPartition> source)
+        public static (global::System.Collections.Generic.IReadOnlyList<FlattenedUnionWithPartition.Keyword> Keyword, global::System.Collections.Generic.IReadOnlyList<FlattenedUnionWithPartition.Integer> Integer) Partition(this global::System.Collections.Generic.IEnumerable<FlattenedUnionWithPartition> source)
         {
             var keywordItems = new global::System.Collections.Generic.List<FlattenedUnionWithPartition.Keyword>();
             var integerItems = new global::System.Collections.Generic.List<FlattenedUnionWithPartition.Integer>();
diff --git a/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=UnionWithPartitionUsage.01.verified.cs b/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=UnionWithPartitionUsage.01.verified.cs
index ed7144c..be2fb07 100644
--- a/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=UnionWithPartitionUsage.01.verified.cs
+++ b/Funcky.DiscriminatedUnion.Test/SourceGeneratorTest.GeneratesExpectedSourceCode_sourceFileName=UnionWithPartitionUsage.01.verified.cs
@@ -43,7 +43,7 @@ partial record Error
     [global::System.CodeDom.Compiler.GeneratedCode("Funcky.DiscriminatedUnion.SourceGeneration", "1.2.0.0")]
     public static partial class UnionWithPartitionUsageEnumerableExtensions
     {
-        public static (global::System.Collections.Generic.IReadOnlyList<UnionWithPartitionUsage.Success> success, global::System.Collections.Generic.IReadOnlyList<UnionWithPartitionUsage.Warning> warning, global::System.Collections.Generic.IReadOnlyList<UnionWithPartitionUsage.Error> error) Partition(this global::System.Collections.Generic.IEnumerable<UnionWithPartitionUsage> source)
+        public static (global::System.Collections.Generic.IReadOnlyList<UnionWithPartitionUsage.Success> Success, global::System.Collections.Generic.IReadOnlyList<UnionWithPartitionUsage.Warning> Warning, global::System.Collections.Generic.IReadOnlyList<UnionWithPartitionUsage.Error> Error) Partition(this global::System.Collections.Generic.IEnumerable<UnionWithPartitionUsage> source)
         {
             var successItems = new global::System.Collections.Generic.List<UnionWithPartitionUsage.Success>();
             var warningItems = new global::System.Collections.Generic.List<UnionWithPartitionUsage.Warning>();