diff --git a/Libraries/src/Amazon.Lambda.RuntimeSupport/Client/RuntimeApiHeaders.cs b/Libraries/src/Amazon.Lambda.RuntimeSupport/Client/RuntimeApiHeaders.cs
index 4609a93bf..d76ae19cd 100644
--- a/Libraries/src/Amazon.Lambda.RuntimeSupport/Client/RuntimeApiHeaders.cs
+++ b/Libraries/src/Amazon.Lambda.RuntimeSupport/Client/RuntimeApiHeaders.cs
@@ -45,12 +45,14 @@ public RuntimeApiHeaders(Dictionary<string, IEnumerable<string>> headers)
 
         private string GetHeaderValueRequired(Dictionary<string, IEnumerable<string>> headers, string header)
         {
-            return headers[header].FirstOrDefault();
+            var headerKey = headers.Keys.FirstOrDefault(k => string.Equals(k, header, StringComparison.OrdinalIgnoreCase));
+            return headers[headerKey].FirstOrDefault();
         }
 
         private string GetHeaderValueOrNull(Dictionary<string, IEnumerable<string>> headers, string header)
         {
-            if (headers.TryGetValue(header, out var values))
+             var headerKey = headers.Keys.FirstOrDefault(k => string.Equals(k, header, StringComparison.OrdinalIgnoreCase));
+            if (headers.TryGetValue(headerKey, out var values))
             {
                 return values.FirstOrDefault();
             }
@@ -58,5 +60,4 @@ private string GetHeaderValueOrNull(Dictionary<string, IEnumerable<string>> head
             return null;
         }
     }
-
 }