diff --git a/src/Microsoft.AspNetCore.OData/Formatter/ODataOutputFormatter.cs b/src/Microsoft.AspNetCore.OData/Formatter/ODataOutputFormatter.cs
index d664d1df9..d9255bfed 100644
--- a/src/Microsoft.AspNetCore.OData/Formatter/ODataOutputFormatter.cs
+++ b/src/Microsoft.AspNetCore.OData/Formatter/ODataOutputFormatter.cs
@@ -194,7 +194,8 @@ public override void WriteResponseHeaders(OutputFormatterWriteContext context)
             // Set the character set.
             MediaTypeHeaderValue currentContentType = GetContentType(response.Headers[HeaderNames.ContentType].FirstOrDefault());
             RequestHeaders requestHeader = request.GetTypedHeaders();
-            if (requestHeader != null && requestHeader.AcceptCharset != null)
+            // Starting from ASP .NET Core 3.0 AcceptCharset returns an empty collection instead of null.
+            if (requestHeader?.AcceptCharset.Count > 0)
             {
                 IEnumerable<string> acceptCharsetValues = requestHeader.AcceptCharset.Select(cs => cs.Value.Value);
 
diff --git a/test/Microsoft.AspNetCore.OData.E2E.Tests/Enums/EnumsTest.cs b/test/Microsoft.AspNetCore.OData.E2E.Tests/Enums/EnumsTest.cs
index 71e316561..01055c8b3 100644
--- a/test/Microsoft.AspNetCore.OData.E2E.Tests/Enums/EnumsTest.cs
+++ b/test/Microsoft.AspNetCore.OData.E2E.Tests/Enums/EnumsTest.cs
@@ -178,6 +178,32 @@ public async Task QueryEntitySetCount(string requestUri, int expectedCount)
             Assert.Equal<int>(expectedCount, int.Parse(count));
         }
 
+        [Theory]
+        [InlineData("/convention/Employees/$count", true)]
+        [InlineData("/convention/Employees/$count", false)]
+        public async Task QueryEntitySetCountEncoding(string requestUri, bool sendAcceptCharset)
+        {
+            // Arrange
+            await ResetDatasource();
+            HttpClient client = CreateClient();
+            client.DefaultRequestHeaders.AcceptCharset.Clear();
+            if (sendAcceptCharset)
+            {
+                client.DefaultRequestHeaders.AcceptCharset.ParseAdd("utf-8");
+            }
+
+            // Act
+            HttpResponseMessage response = await client.GetAsync(requestUri);
+
+            // Assert
+            Assert.True(response.IsSuccessStatusCode);
+            var blob = await response.Content.ReadAsByteArrayAsync();
+            Assert.Equal("utf-8", response.Content.Headers.ContentType.CharSet, StringComparer.OrdinalIgnoreCase);
+            var count = Encoding.UTF8.GetString(blob);
+            Assert.Equal(3, int.Parse(count));
+            Assert.False((blob[0] == 0xEF) && (blob[1] == 0xBB) && (blob[2] == 0xBF));
+        }
+
         [Theory]
         [InlineData("/convention/Employees(1)/SkillSet/$count", 2)]
         [InlineData("/convention/Employees(1)/SkillSet/$count?$filter=$it eq Microsoft.AspNetCore.OData.E2E.Tests.Enums.Skill'Sql'", 1)]