diff --git a/Octokit.Tests/Exceptions/AbuseExceptionTests.cs b/Octokit.Tests/Exceptions/AbuseExceptionTests.cs
index 17b2616c14..80285bc11f 100644
--- a/Octokit.Tests/Exceptions/AbuseExceptionTests.cs
+++ b/Octokit.Tests/Exceptions/AbuseExceptionTests.cs
@@ -53,6 +53,17 @@ public void WithRetryAfterHeader_PopulatesRetryAfterSeconds()
                         Assert.Equal(30, abuseException.RetryAfterSeconds);
                     }
 
+                    [Fact]
+                    public void WithRetryAfterCaseInsensitiveHeader_PopulatesRetryAfterSeconds()
+                    {
+                        var headerDictionary = new Dictionary<string, string> { { "retry-after", "20" } };
+
+                        var response = new Response(HttpStatusCode.Forbidden, null, headerDictionary, "application/json");
+                        var abuseException = new AbuseException(response);
+
+                        Assert.Equal(20, abuseException.RetryAfterSeconds);
+                    }
+
                     [Fact]
                     public void WithZeroHeaderValue_RetryAfterSecondsIsZero()
                     {
diff --git a/Octokit/Exceptions/AbuseException.cs b/Octokit/Exceptions/AbuseException.cs
index 8fceec4f3a..5e94754b95 100644
--- a/Octokit/Exceptions/AbuseException.cs
+++ b/Octokit/Exceptions/AbuseException.cs
@@ -1,6 +1,8 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using System.Net;
 #if !NO_SERIALIZABLE
 using System.Runtime.Serialization;
@@ -44,11 +46,11 @@ public AbuseException(IResponse response, Exception innerException)
 
         private static int? ParseRetryAfterSeconds(IResponse response)
         {
-            string secondsValue;
-            if (!response.Headers.TryGetValue("Retry-After", out secondsValue)) { return null; }
+            var header = response.Headers.FirstOrDefault(h => string.Equals(h.Key, "Retry-After", StringComparison.OrdinalIgnoreCase));
+            if (header.Equals(default(KeyValuePair<string, string>))) { return null; }
 
             int retrySeconds;
-            if (!int.TryParse(secondsValue, out retrySeconds)) { return null; }
+            if (!int.TryParse(header.Value, out retrySeconds)) { return null; }
             if (retrySeconds < 0) { return null; }
 
             return retrySeconds;