diff --git a/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.cs b/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.cs
index d041705a19..e1175fcde9 100644
--- a/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.cs
+++ b/src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.cs
@@ -27,6 +27,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             get { return _contentLength; }
             set
             {
+                if (_isReadOnly)
+                {
+                    ThrowHeadersReadOnlyException();
+                }
                 if (value.HasValue && value.Value < 0)
                 {
                     ThrowInvalidContentLengthException(value.Value);
diff --git a/src/Servers/Kestrel/Core/test/HttpResponseHeadersTests.cs b/src/Servers/Kestrel/Core/test/HttpResponseHeadersTests.cs
index ed3c492e3c..1bbe06e99c 100644
--- a/src/Servers/Kestrel/Core/test/HttpResponseHeadersTests.cs
+++ b/src/Servers/Kestrel/Core/test/HttpResponseHeadersTests.cs
@@ -138,6 +138,15 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
             Assert.Throws<InvalidOperationException>(() => ((IDictionary<string, StringValues>)headers).Add("my-header", new[] { "value" }));
         }
 
+        [Fact]
+        public void ThrowsWhenSettingContentLengthPropertyAfterReadOnlyIsSet()
+        {
+            var headers = new HttpResponseHeaders();
+            headers.SetReadOnly();
+
+            Assert.Throws<InvalidOperationException>(() => headers.ContentLength = null);
+        }
+
         [Fact]
         public void ThrowsWhenChangingHeaderAfterReadOnlyIsSet()
         {