diff --git a/src/System.Net.Http/src/System/Net/Http/Unix/CurlResponseHeaderReader.cs b/src/System.Net.Http/src/System/Net/Http/Unix/CurlResponseHeaderReader.cs
index 46b5b09e27b5..9ed8ec7b8b45 100644
--- a/src/System.Net.Http/src/System/Net/Http/Unix/CurlResponseHeaderReader.cs
+++ b/src/System.Net.Http/src/System/Net/Http/Unix/CurlResponseHeaderReader.cs
@@ -78,9 +78,17 @@ public bool ReadHeader(out string headerName, out string headerValue)
 
             if (index > 0)
             {
+                // For compatability, skip past any whitespace before the colon, even though
+                // the RFC suggests there shouldn't be any.
+                int headerNameLength = index;
+                while (index < _span.Length && IsWhiteSpaceLatin1(_span[index]))
+                {
+                    index++;
+                }
+
                 CheckResponseMsgFormat(index < _span.Length);
                 CheckResponseMsgFormat(_span[index] == ':');
-                HeaderBufferSpan headerNameSpan = _span.Substring(0, index);
+                HeaderBufferSpan headerNameSpan = _span.Substring(0, headerNameLength);
                 if (!HttpKnownHeaderNames.TryGetHeaderName(_span.Buffer, _span.Length, out headerName))
                 {
                     headerName = headerNameSpan.ToString();
@@ -111,6 +119,19 @@ private static bool ValidHeaderNameChar(byte c)
             return c > ' ' && invalidChars.IndexOf((char)c) < 0;
         }
 
+        internal static bool IsWhiteSpaceLatin1(byte c)
+        {
+            // SPACE
+            // U+0009 = <control> HORIZONTAL TAB
+            // U+000a = <control> LINE FEED
+            // U+000b = <control> VERTICAL TAB
+            // U+000c = <control> FORM FEED
+            // U+000d = <control> CARRIAGE RETURN
+            // U+0085 = <control> NEXT LINE
+            // U+00a0 = NO-BREAK SPACE
+            return c == ' ' || (c >= '\x0009' && c <= '\x000d') || c == '\x00a0' || c == '\x0085';
+        }
+
         private unsafe struct HeaderBufferSpan
         {
             private readonly byte* _pointer;
@@ -268,18 +289,6 @@ public override string ToString()
             {
                 return Length == 0 ? string.Empty : HttpRuleParser.DefaultHttpEncoding.GetString(_pointer, Length);
             }
-
-            private static bool IsWhiteSpaceLatin1(byte c)
-            {
-                // U+0009 = <control> HORIZONTAL TAB
-                // U+000a = <control> LINE FEED
-                // U+000b = <control> VERTICAL TAB
-                // U+000c = <control> FORM FEED
-                // U+000d = <control> CARRIAGE RETURN
-                // U+0085 = <control> NEXT LINE
-                // U+00a0 = NO-BREAK SPACE
-                return c == ' ' || (c >= '\x0009' && c <= '\x000d') || c == '\x00a0' || c == '\x0085';
-            }
         }
     }
 }
diff --git a/src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs b/src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs
index fd33e143b21e..d4d0c6825757 100644
--- a/src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs
+++ b/src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs
@@ -739,7 +739,7 @@ await LoopbackServer.ReadRequestAndSendResponseAsync(server,
                             $"HTTP/1.1 200 OK\r\n" +
                             $"Date: {DateTimeOffset.UtcNow:R}\r\n" +
                             $"Set-Cookie: {cookie1.Key}={cookie1.Value}; Path=/\r\n" +
-                            $"Set-Cookie: {cookie2.Key}={cookie2.Value}; Path=/\r\n" +
+                            $"Set-Cookie   : {cookie2.Key}={cookie2.Value}; Path=/\r\n" + // space before colon to verify header is trimmed and recognized
                             $"Set-Cookie: {cookie3.Key}={cookie3.Value}; Path=/\r\n" +
                             "\r\n");
 
diff --git a/src/System.Net.Http/tests/UnitTests/Headers/CurlResponseHeaderReaderTest.cs b/src/System.Net.Http/tests/UnitTests/Headers/CurlResponseHeaderReaderTest.cs
index 28b824dd7dc5..42eb666ba3f2 100644
--- a/src/System.Net.Http/tests/UnitTests/Headers/CurlResponseHeaderReaderTest.cs
+++ b/src/System.Net.Http/tests/UnitTests/Headers/CurlResponseHeaderReaderTest.cs
@@ -109,19 +109,34 @@ public unsafe void ReadStatusLine_ValidStatusCodeLine_ResponseMessageVersionSet(
         #endregion
 
         #region Headers
-        [Theory]
-        [InlineData("TestHeader", "Test header value", false)]
-        [InlineData("TestHeader", "Test header value", true)]
-        [InlineData("TestHeader", "", false)]
-        [InlineData("TestHeader", "", true)]
-        [InlineData("Server", "IIS", false)]
-        [InlineData("Server", "IIS", true)]
-        public unsafe void ReadHeader_ValidHeaderLine_HeaderReturned(string expectedHeaderName, string expectedHeaderValue, bool spaceAfterColon)
+        public static IEnumerable<object[]> ReadHeader_ValidHeaderLine_HeaderReturned_MemberData()
         {
-            string headerLine = $"{expectedHeaderName}:{(spaceAfterColon ? " " : "")}{expectedHeaderValue}";
+            var namesAndValues = new KeyValuePair<string, string>[]
+            {
+                new KeyValuePair<string, string>("TestHeader", "Test header value"),
+                new KeyValuePair<string, string>("TestHeader", ""),
+                new KeyValuePair<string, string>("Server", "IIS"),
+                new KeyValuePair<string, string>("Server", "I:I:S"),
+            };
+            var whitespaces = new string[] { "", " ", "    ", " \t" };
+
+            foreach (KeyValuePair<string, string> nameAndValue in namesAndValues)
+            {
+                foreach (string beforeColon in whitespaces) // only "" is valid according to the RFC, but we parse more leniently
+                {
+                    foreach (string afterColon in whitespaces)
+                    {
+                        yield return new object[] { $"{nameAndValue.Key}{beforeColon}:{afterColon}{nameAndValue.Value}", nameAndValue.Key, nameAndValue.Value };
+                    }
+                }
+            }
+        }
 
+        [Theory]
+        [MemberData(nameof(ReadHeader_ValidHeaderLine_HeaderReturned_MemberData))]
+        public unsafe void ReadHeader_ValidHeaderLine_HeaderReturned(string headerLine, string expectedHeaderName, string expectedHeaderValue)
+        {
             byte[] buffer = headerLine.Select(c => checked((byte)c)).ToArray();
-
             fixed (byte* pBuffer = buffer)
             {
                 var reader = new CurlResponseHeaderReader(new IntPtr(pBuffer), checked((ulong)buffer.Length));