diff --git a/news/changelog-1.8.md b/news/changelog-1.8.md
index 48b33d42c84..7e58237e6bc 100644
--- a/news/changelog-1.8.md
+++ b/news/changelog-1.8.md
@@ -12,3 +12,7 @@ All changes included in 1.8:
 
 - ([#12551](https://github.com/quarto-dev/quarto-cli/pull/12551)): Improve warning issued when `aliases` would overwrite an existing document.
 - ([#12616](https://github.com/quarto-dev/quarto-cli/issues/12616)): find SVG images in image discovery for listings.
+
+## Crossrefs
+
+- ([#12615](https://github.com/quarto-dev/quarto-cli/pull/12615)): Adds `algorithm` to theorem environments. (author: @jeremy9959)
diff --git a/src/resources/filters/customnodes/theorem.lua b/src/resources/filters/customnodes/theorem.lua
index a18cf74dccb..e05eca41024 100644
--- a/src/resources/filters/customnodes/theorem.lua
+++ b/src/resources/filters/customnodes/theorem.lua
@@ -40,11 +40,16 @@ theorem_types = {
     style = "definition",
     title = "Example",
   },
-  exr  = {
+  exr = {
     env = "exercise",
     style = "definition",
     title = "Exercise"
-  }
+  },
+  alg = {
+    env = "algorithm",
+    style = "plain",
+    title = "Algorithm"
+  },
 }
 
 function has_theorem_ref(el)
diff --git a/tests/docs/smoke-all/crossrefs/theorem/algorithm.qmd b/tests/docs/smoke-all/crossrefs/theorem/algorithm.qmd
new file mode 100644
index 00000000000..3df6e707adf
--- /dev/null
+++ b/tests/docs/smoke-all/crossrefs/theorem/algorithm.qmd
@@ -0,0 +1,47 @@
+---
+format:
+  typst:
+    keep-typ: true
+_quarto:
+  tests:
+    html:
+      ensureHtmlElements:
+        - 
+          - "a.quarto-xref"
+        - []
+    latex:
+      ensureFileRegexMatches:
+        -
+          - "hypertarget{alg-gcd}"
+          - "label{alg-gcd}"
+          - "Alg.~\\\\ref\\{alg-gcd\\}"
+          - "alg.~\\\\ref\\{alg-gcd\\}"
+        - []
+    typst:
+      ensureTypstFileRegexMatches:
+        - 
+          - "#ref\\(<alg-gcd>, supplement: \\[alg.\\]\\)"
+          - "#ref\\(<alg-gcd>, supplement: \\[Alg.\\]\\)"
+          - "#algorithm\\(\"Euclid\"\\)"
+        - []
+    markdown:
+      ensureFileRegexMatches:
+        -
+          - "\\[alg. 1\\]\\(#alg-gcd\\)\\{.quarto-xref\\}" # note the non-breaking space in "alg. 1"
+          - '\[\*\*Algorithm 1 \(Euclid\)\*\*\]\{.theorem-title\}'
+---
+
+::: {#alg-gcd}
+
+## Euclid
+
+```
+gcd(a, b) =
+  if b == 0 then return a
+  return gcd(b, a mod b)
+```
+
+:::
+
+
+See @alg-gcd. @Alg-gcd has been known since the antiquity.
\ No newline at end of file