diff --git a/packages/opencode/src/installation/index.ts b/packages/opencode/src/installation/index.ts
index d18c9e31a..47278bd56 100644
--- a/packages/opencode/src/installation/index.ts
+++ b/packages/opencode/src/installation/index.ts
@@ -148,6 +148,16 @@ export namespace Installation {
         break
       case "brew": {
         const formula = await getBrewFormula()
+        if (formula.includes("/")) {
+          cmd =
+            $`brew tap anomalyco/tap && cd "$(brew --repo anomalyco/tap)" && git pull --ff-only && brew upgrade ${formula}`.env(
+              {
+                HOMEBREW_NO_AUTO_UPDATE: "1",
+                ...process.env,
+              },
+            )
+          break
+        }
         cmd = $`brew upgrade ${formula}`.env({
           HOMEBREW_NO_AUTO_UPDATE: "1",
           ...process.env,
@@ -188,14 +198,19 @@ export namespace Installation {
 
     if (detectedMethod === "brew") {
       const formula = await getBrewFormula()
-      if (formula === "opencode") {
-        return fetch("https://formulae.brew.sh/api/formula/opencode.json")
-          .then((res) => {
-            if (!res.ok) throw new Error(res.statusText)
-            return res.json()
-          })
-          .then((data: any) => data.versions.stable)
+      if (formula.includes("/")) {
+        const infoJson = await $`brew info --json=v2 ${formula}`.quiet().text()
+        const info = JSON.parse(infoJson)
+        const version = info.formulae?.[0]?.versions?.stable
+        if (!version) throw new Error(`Could not detect version for tap formula: ${formula}`)
+        return version
       }
+      return fetch("https://formulae.brew.sh/api/formula/opencode.json")
+        .then((res) => {
+          if (!res.ok) throw new Error(res.statusText)
+          return res.json()
+        })
+        .then((data: any) => data.versions.stable)
     }
 
     if (detectedMethod === "npm" || detectedMethod === "bun" || detectedMethod === "pnpm") {