diff --git a/lib/index.js b/lib/index.js
index f14cd6e..7db8dcf 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -30,15 +30,12 @@ class IntegrityStream extends MiniPass {
 
     // options used for calculating stream.  can't be changed.
     if (opts?.algorithms) {
-      this.algorithms = Array.from(
-        new Set(opts.algorithms.concat(this.algorithm ? [this.algorithm] : []))
-      )
+      this.algorithms = [...opts.algorithms]
     } else {
       this.algorithms = [...DEFAULT_ALGORITHMS]
-
-      if (this.algorithm !== null && this.algorithm !== DEFAULT_ALGORITHMS[0]) {
-        this.algorithms.push(this.algorithm)
-      }
+    }
+    if (this.algorithm !== null && !this.algorithms.includes(this.algorithm)) {
+      this.algorithms.push(this.algorithm)
     }
 
     this.hashes = this.algorithms.map(crypto.createHash)