diff --git a/fdk/constants.py b/fdk/constants.py
index d470657..45dca28 100644
--- a/fdk/constants.py
+++ b/fdk/constants.py
@@ -36,17 +36,16 @@
 OCI_TRACING_ENABLED = "OCI_TRACING_ENABLED"
 
 
-# headers are lower case TODO(denis): why?
-FN_INTENT = "fn-intent"
-FN_HTTP_PREFIX = "fn-http-h-"
-FN_HTTP_STATUS = "fn-http-status"
-FN_DEADLINE = "fn-deadline"
-FN_FDK_VERSION = "fn-fdk-version"
-FN_HTTP_REQUEST_URL = "fn-http-request-url"
-FN_CALL_ID = "fn-call-id"
-FN_HTTP_METHOD = "fn-http-method"
-CONTENT_TYPE = "content-type"
-CONTENT_LENGTH = "content-length"
+FN_INTENT = "Fn-Intent"
+FN_HTTP_PREFIX = "Fn-Http-H-"
+FN_HTTP_STATUS = "Fn-Http-Status"
+FN_DEADLINE = "Fn-Deadline"
+FN_FDK_VERSION = "Fn-Fdk-Version"
+FN_HTTP_REQUEST_URL = "Fn-Http-Request-Url"
+FN_CALL_ID = "Fn-Call-Id"
+FN_HTTP_METHOD = "Fn-Http-Method"
+CONTENT_TYPE = "Content-Type"
+CONTENT_LENGTH = "Content-Length"
 X_B3_TRACEID = "x-b3-traceid"
 X_B3_SPANID = "x-b3-spanid"
 X_B3_PARENTSPANID = "x-b3-parentspanid"