diff --git a/Saule/Queries/Fieldset/FieldsetProperty.cs b/Saule/Queries/Fieldset/FieldsetProperty.cs
index e3f523b..1999ffa 100644
--- a/Saule/Queries/Fieldset/FieldsetProperty.cs
+++ b/Saule/Queries/Fieldset/FieldsetProperty.cs
@@ -1,4 +1,6 @@
-namespace Saule.Queries.Fieldset
+using System.Linq;
+
+namespace Saule.Queries.Fieldset
 {
     /// <summary>
     /// Property for fieldset
@@ -13,7 +15,7 @@ public class FieldsetProperty
         public FieldsetProperty(string type, string[] fields)
         {
             Type = type;
-            Fields = fields;
+            Fields = fields.Select(f => f.ToComparablePropertyName()).ToArray();
         }
 
         /// <summary>
diff --git a/Saule/Serialization/ResourceSerializer.cs b/Saule/Serialization/ResourceSerializer.cs
index 0046edb..8a5873c 100644
--- a/Saule/Serialization/ResourceSerializer.cs
+++ b/Saule/Serialization/ResourceSerializer.cs
@@ -300,7 +300,7 @@ private JObject SerializeAttributes(ResourceGraphNode node, FieldsetProperty fie
         {
             var attributeHash = node.Resource.Attributes
                 .Where(a =>
-                    node.SourceObject.IncludesProperty(_propertyNameConverter.ToModelPropertyName(a.InternalName)) && fieldset.Fields.Contains(_propertyNameConverter.ToModelPropertyName(a.InternalName)))
+                    node.SourceObject.IncludesProperty(_propertyNameConverter.ToModelPropertyName(a.InternalName)) && fieldset.Fields.Contains(a.InternalName.ToComparablePropertyName()))
                 .Select(a =>
                     new
                     {
diff --git a/Saule/StringExtensions.cs b/Saule/StringExtensions.cs
index 88b2a2c..80ae54e 100644
--- a/Saule/StringExtensions.cs
+++ b/Saule/StringExtensions.cs
@@ -57,6 +57,11 @@ public static string ToCamelCase(this string source)
             return string.Join(string.Empty, cased.ToArray());
         }
 
+        public static string ToComparablePropertyName(this string propertyName)
+        {
+            return propertyName.Replace("_", string.Empty).Replace("-", string.Empty).ToUpperInvariant();
+        }
+
         public static string SubstringToSeperator(this string source, string seperator)
         {
             var to = source.IndexOf(seperator);
diff --git a/Tests/JsonApiSerializerTests.cs b/Tests/JsonApiSerializerTests.cs
index 1edb5d0..adddd9e 100644
--- a/Tests/JsonApiSerializerTests.cs
+++ b/Tests/JsonApiSerializerTests.cs
@@ -84,6 +84,28 @@ public void UsesQueryFieldsetExpressions()
             Assert.Null(result["data"][0]["attributes"]["number-of-employees"]);
         }
 
+        [Theory(DisplayName = "Uses query fieldset expressions if specified with various input string cases.")]
+        [InlineData("?fields[corporation]=name,NumberOfEmployees")]
+        [InlineData("?fields[corporation]=name,numberofemployees")]
+        [InlineData("?fields[corporation]=name,NUMBEROFEMPLOYEES")]
+        [InlineData("?fields[corporation]=name,numberOfEmployees")]
+        [InlineData("?fields[corporation]=name,number-of-employees")]
+        [InlineData("?fields[corporation]=name,number_of_employees")]
+        public void UsesQueryFieldsetExpressionsFieldsFormatCases(string query)
+        {
+            var target = new JsonApiSerializer<CompanyResource>
+            {
+                AllowQuery = true
+            };
+            var companies = Get.Companies(1).ToList();
+            var result = target.Serialize(companies, new Uri(DefaultUrl, query));
+            _output.WriteLine(result.ToString());
+
+            Assert.NotNull(result["data"][0]["attributes"]["name"]);
+            Assert.Null(result["data"][0]["attributes"]["location"]);
+            Assert.NotNull(result["data"][0]["attributes"]["number-of-employees"]);
+        }
+
         [Fact(DisplayName = "Returns no fields if requested field is not part of that model")]
         public void ReturnEmptyModelForUnknownFieldsetExpressions()
         {