diff --git a/module.d.ts b/module.d.ts
index f906b0b..ecfa99e 100644
--- a/module.d.ts
+++ b/module.d.ts
@@ -8,7 +8,7 @@ declare module "activitypub-http-signatures" {
     export class Sha256Signer {
         constructor(options: { publicKeyId: string, privateKey: string, headerNames?: string[] });
 
-        sign: (options: { url: string, method: string, headers: any[] }) => string;
+        sign: (options: { url: string, method: string, headers: HeadersInit }) => string;
     };
 
     type parse = (params: { url: string, method: string, headers: Record<string, string> }) => {
diff --git a/src/net.ts b/src/net.ts
index 94d3042..f5fdc40 100644
--- a/src/net.ts
+++ b/src/net.ts
@@ -19,24 +19,22 @@ export interface SignedInit {
 
 // TODO: Handle redirects.
 export const signedFetch = async (url: string, init: RequestInit, signedInit: SignedInit): Promise<globalThis.Response> => {
-    const signedHeaders: HeadersInit = [
-        ["Date", new Date().toUTCString()]
-    ];
+    const signedHeaders: HeadersInit = {};
 
     const headerNames = ["(request-target)", "host", "date"];
 
     if (init.method === "POST") {
         headerNames.push("content-type", "digest");
 
-        signedHeaders.push(["Content-Type", `application/ld+json; profile="${CONTEXT}"`]);
+        signedHeaders["content-type"] = `application/ld+json; profile="${CONTEXT}"`;
 
         if (init.body) {
             if (signedInit.digest) {
-                signedHeaders.push(["Digest", signedInit.digest]);
+                signedHeaders["digest"] = signedInit.digest;
             }
             else {
                 if (Buffer.isBuffer(init.body) || typeof init.body === "string") {
-                    signedHeaders.push(["Digest", hashDigest(init.body)]);
+                    signedHeaders["digest"] = hashDigest(init.body);
                 }
                 else throw "unsupported body type";
             }
@@ -53,19 +51,29 @@ export const signedFetch = async (url: string, init: RequestInit, signedInit: Si
     const signature = signer.sign({
         url,
         method: init.method as string,
-        headers: [
-            ["Host", new URL(url).host],
-            ...signedHeaders
-        ]
+        headers: signedHeaders
     });
 
+    // Retain order for picky servers.
+
     const newHeaders: HeadersInit = 
         [
-            ...signedHeaders,
-            ["Signature", signature]
+            ["date", signedHeaders.date],
         ]
     ;
 
+    if (signedHeaders["content-type"]) newHeaders.push([
+        "content-type",
+        signedHeaders["content-type"]
+    ]);
+
+    if (signedHeaders.digest) newHeaders.push([
+        "digest",
+        signedHeaders.digest
+    ]);
+
+    newHeaders.push(["signature", signature]);
+
     if (Array.isArray(init.headers))
         init.headers
             .filter((header) => Array.isArray(header))