diff --git a/cli/js/io.ts b/cli/js/io.ts
index 0237181002fcc7..6cd957b763cc6c 100644
--- a/cli/js/io.ts
+++ b/cli/js/io.ts
@@ -68,8 +68,7 @@ export interface ReadWriteCloser extends Reader, Writer, Closer {}
 // https://golang.org/pkg/io/#ReadWriteSeeker
 export interface ReadWriteSeeker extends Reader, Writer, Seeker {}
 
-// https://golang.org/pkg/io/#Copy
-export async function copy(dst: Writer, src: Reader): Promise<number> {
+export async function copy(src: Reader, dst: Writer): Promise<number> {
   let n = 0;
   const b = new Uint8Array(32 * 1024);
   let gotEOF = false;
diff --git a/cli/js/lib.deno.ns.d.ts b/cli/js/lib.deno.ns.d.ts
index 9980790b3376a3..fb0f8eefc6fe5b 100644
--- a/cli/js/lib.deno.ns.d.ts
+++ b/cli/js/lib.deno.ns.d.ts
@@ -565,16 +565,16 @@ declare namespace Deno {
    *
    *       const source = await Deno.open("my_file.txt");
    *       const buffer = new Deno.Buffer()
-   *       const bytesCopied1 = await Deno.copy(Deno.stdout, source);
-   *       const bytesCopied2 = await Deno.copy(buffer, source);
+   *       const bytesCopied1 = await Deno.copy(source, Deno.stdout);
+   *       const bytesCopied2 = await Deno.copy(source, buffer);
    *
    * Because `copy()` is defined to read from `src` until `EOF`, it does not
    * treat an `EOF` from `read()` as an error to be reported.
    *
-   * @param dst The destination to copy to
    * @param src The source to copy from
+   * @param dst The destination to copy to
    */
-  export function copy(dst: Writer, src: Reader): Promise<number>;
+  export function copy(src: Reader, dst: Writer): Promise<number>;
 
   /** **UNSTABLE**: new API, yet to be vetted
    * Turns a Reader, `r`, into an async iterator.
diff --git a/cli/js/tests/files_test.ts b/cli/js/tests/files_test.ts
index f68e5def4732c0..a095216b0779a4 100644
--- a/cli/js/tests/files_test.ts
+++ b/cli/js/tests/files_test.ts
@@ -18,7 +18,7 @@ unitTest({ perms: { read: true } }, async function filesCopyToStdout(): Promise<
   const filename = "cli/tests/fixture.json";
   const file = await Deno.open(filename);
   assert(file.rid > 2);
-  const bytesWritten = await Deno.copy(Deno.stdout, file);
+  const bytesWritten = await Deno.copy(file, Deno.stdout);
   const fileSize = Deno.statSync(filename).size;
   assertEquals(bytesWritten, fileSize);
   console.log("bytes written", bytesWritten);
diff --git a/cli/tests/cat.ts b/cli/tests/cat.ts
index 756238be61a93f..bd6b5af06c2293 100644
--- a/cli/tests/cat.ts
+++ b/cli/tests/cat.ts
@@ -4,7 +4,7 @@ async function main(): Promise<void> {
   for (let i = 1; i < args.length; i++) {
     const filename = args[i];
     const file = await open(filename);
-    await copy(stdout, file);
+    await copy(file, stdout);
   }
 }
 
diff --git a/std/archive/tar.ts b/std/archive/tar.ts
index cafef8723a4c5f..6bc2b92d0bfe27 100644
--- a/std/archive/tar.ts
+++ b/std/archive/tar.ts
@@ -470,7 +470,7 @@ export class Untar {
     while (rest > 0) {
       await this.reader.readFull(this.block);
       const arr = rest < recordSize ? this.block.subarray(0, rest) : this.block;
-      await Deno.copy(writer, new Deno.Buffer(arr));
+      await Deno.copy(new Deno.Buffer(arr), writer);
       rest -= recordSize;
     }
 
diff --git a/std/archive/tar_test.ts b/std/archive/tar_test.ts
index ae3ee8138c0b58..cd22addcc80b43 100644
--- a/std/archive/tar_test.ts
+++ b/std/archive/tar_test.ts
@@ -30,8 +30,8 @@ Deno.test(async function createTarArchive(): Promise<void> {
   await tar.append("dir/tar.ts", { filePath });
 
   // write tar data to a buffer
-  const writer = new Deno.Buffer(),
-    wrote = await Deno.copy(writer, tar.getReader());
+  const writer = new Deno.Buffer();
+  const wrote = await Deno.copy(tar.getReader(), writer);
 
   /**
    * 3072 = 512 (header) + 512 (content) + 512 (header) + 512 (content)
diff --git a/std/examples/cat.ts b/std/examples/cat.ts
index 7b7af3145cd89e..cf9a7cb1d5f54a 100644
--- a/std/examples/cat.ts
+++ b/std/examples/cat.ts
@@ -2,6 +2,6 @@
 const filenames = Deno.args;
 for (const filename of filenames) {
   const file = await Deno.open(filename);
-  await Deno.copy(Deno.stdout, file);
+  await Deno.copy(file, Deno.stdout);
   file.close();
 }
diff --git a/std/examples/curl.ts b/std/examples/curl.ts
index 44ee66125e0b67..a3e8b73db37ab3 100644
--- a/std/examples/curl.ts
+++ b/std/examples/curl.ts
@@ -3,7 +3,7 @@ const url_ = Deno.args[0];
 const res = await fetch(url_);
 
 // TODO(ry) Re-enable streaming in this example.
-// Originally we did: await Deno.copy(Deno.stdout, res.body);
+// Originally we did: await Deno.copy(res.body, Deno.stdout);
 // But maybe more JS-y would be: res.pipeTo(Deno.stdout);
 
 const body = new Uint8Array(await res.arrayBuffer());
diff --git a/std/http/io.ts b/std/http/io.ts
index 37285fdbf87592..2c2fea48a998db 100644
--- a/std/http/io.ts
+++ b/std/http/io.ts
@@ -273,7 +273,7 @@ export async function writeResponse(
     const contentLength = headers.get("content-length");
     assert(contentLength != null);
     const bodyLength = parseInt(contentLength);
-    const n = await Deno.copy(writer, r.body);
+    const n = await Deno.copy(r.body, writer);
     assert(n === bodyLength);
   } else {
     await writeChunkedBody(writer, r.body);
diff --git a/std/io/readers_test.ts b/std/io/readers_test.ts
index 22982c92499f24..041fd78a87fa22 100644
--- a/std/io/readers_test.ts
+++ b/std/io/readers_test.ts
@@ -33,6 +33,6 @@ test(async function ioMultiReader(): Promise<void> {
   const n = await copyN(w, r, 4);
   assertEquals(n, 4);
   assertEquals(w.toString(), "abcd");
-  await copy(w, r);
+  await copy(r, w);
   assertEquals(w.toString(), "abcdef");
 });
diff --git a/std/io/writers_test.ts b/std/io/writers_test.ts
index 916ad043e9c3aa..96dc044ae95008 100644
--- a/std/io/writers_test.ts
+++ b/std/io/writers_test.ts
@@ -9,6 +9,6 @@ test(async function ioStringWriter(): Promise<void> {
   const r = new StringReader("0123456789");
   await copyN(w, r, 4);
   assertEquals(w.toString(), "base0123");
-  await copy(w, r);
+  await copy(r, w);
   assertEquals(w.toString(), "base0123456789");
 });
diff --git a/std/mime/multipart.ts b/std/mime/multipart.ts
index c46948226b3a19..7097522903f103 100644
--- a/std/mime/multipart.ts
+++ b/std/mime/multipart.ts
@@ -308,7 +308,7 @@ export class MultipartReader {
       }
       // file
       let formFile: FormFile | undefined;
-      const n = await copy(buf, p);
+      const n = await copy(p, buf);
       const contentType = p.headers.get("content-type");
       assert(contentType != null, "content-type must be set");
       if (n > maxMemory) {
@@ -573,7 +573,7 @@ export class MultipartWriter {
     file: Reader
   ): Promise<void> {
     const f = await this.createFormFile(field, filename);
-    await copy(f, file);
+    await copy(file, f);
   }
 
   private flush(): Promise<void> {
diff --git a/std/mime/multipart_test.ts b/std/mime/multipart_test.ts
index 8b721a44144908..aa3b7524eba355 100644
--- a/std/mime/multipart_test.ts
+++ b/std/mime/multipart_test.ts
@@ -208,7 +208,7 @@ test({
       assert(file.tempfile != null);
       const f = await open(file.tempfile);
       const w = new StringWriter();
-      await copy(w, f);
+      await copy(f, w);
       const json = JSON.parse(w.toString());
       assertEquals(json["compilerOptions"]["target"], "es2018");
       f.close();