diff --git a/README.md b/README.md
index e1cb911..cba82e8 100644
--- a/README.md
+++ b/README.md
@@ -282,7 +282,7 @@ let jws = try JWS(payload: payload, key: key)
 
 let jwsString = jws.compactSerialization
 
-try JWS(jwsString: jwsString).verify(key: keyJWK)
+try JWS(jwsString: jwsString).verify(key: key)
 ```
 
 If you want to add additional headers beyond the default to the JWS:
diff --git a/Sources/JSONWebToken/JWT+Encryption.swift b/Sources/JSONWebToken/JWT+Encryption.swift
index 3057db1..7abb1a0 100644
--- a/Sources/JSONWebToken/JWT+Encryption.swift
+++ b/Sources/JSONWebToken/JWT+Encryption.swift
@@ -54,7 +54,9 @@ extension JWT {
         additionalAuthenticationData: Data? = nil
     ) throws -> JWT {
         var protectedHeader = protectedHeader
-        protectedHeader.type = "JWT"
+        if protectedHeader.type == nil {
+            protectedHeader.type = "JWT"
+        }
         let encodedPayload = try JSONEncoder.jwt.encode(payload)
         return JWT(
             payload: encodedPayload,
@@ -86,7 +88,9 @@ extension JWT {
         additionalAuthenticationData: Data? = nil
     ) throws -> JWT {
         var protectedHeader = protectedHeader
-        protectedHeader.type = "JWT"
+        if protectedHeader.type == nil {
+            protectedHeader.type = "JWT"
+        }
         let encodedPayload = try JSONEncoder.jwt.encode(payload().value)
         return JWT(
             payload: encodedPayload,
@@ -139,7 +143,9 @@ extension JWT {
         additionalAuthenticationData: Data? = nil
     ) throws -> JWE {
         var protectedHeader = protectedHeader
-        protectedHeader.contentType = "JWT"
+        if protectedHeader.contentType == nil {
+            protectedHeader.contentType = "JWT"
+        }
         
         return try JWE(
             payload: jwt.jwtString.tryToData(),
diff --git a/Sources/JSONWebToken/JWT+Signing.swift b/Sources/JSONWebToken/JWT+Signing.swift
index be1410b..98fe99e 100644
--- a/Sources/JSONWebToken/JWT+Signing.swift
+++ b/Sources/JSONWebToken/JWT+Signing.swift
@@ -40,7 +40,9 @@ extension JWT {
         key: Key?
     ) throws -> JWT {
         var protectedHeader = protectedHeader
-        protectedHeader.type = "JWT"
+        if protectedHeader.type == nil {
+            protectedHeader.type = "JWT"
+        }
         let encodedPayload = try JSONEncoder.jwt.encode(payload)
         return JWT(
             payload: encodedPayload,
@@ -72,7 +74,9 @@ extension JWT {
         key: Key?
     ) throws -> JWT {
         var protectedHeader = protectedHeader
-        protectedHeader.type = "JWT"
+        if protectedHeader.type == nil {
+            protectedHeader.type = "JWT"
+        }
         let encodedPayload = try JSONEncoder.jwt.encode(payload().value)
         return JWT(
             payload: encodedPayload,
@@ -179,7 +183,9 @@ extension JWT {
         key: KeyRepresentable?
     ) throws -> JWS {
         var protectedHeader = protectedHeader
-        protectedHeader.contentType = "JWT"
+        if protectedHeader.contentType == nil {
+            protectedHeader.contentType = "JWT"
+        }
         
         return try JWS(
             payload: JSONEncoder.jwt.encode(jwtString.tryToData()),