diff --git a/package-lock.json b/package-lock.json
index caa0831..53c651a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@webpod/ps",
-  "version": "0.0.0-beta.3",
+  "version": "0.0.0-beta.6",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@webpod/ps",
-      "version": "0.0.0-beta.3",
+      "version": "0.0.0-beta.6",
       "license": "MIT",
       "dependencies": {
         "@webpod/ingrid": "^0.0.0-beta.3",
diff --git a/package.json b/package.json
index 6d14633..829c18c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@webpod/ps",
-  "version": "0.0.0-beta.5",
+  "version": "0.0.0-beta.6",
   "description": "A process lookup utility",
   "publishConfig": {
     "access": "public"
diff --git a/src/main/ts/ps.ts b/src/main/ts/ps.ts
index 7606017..51f15e7 100644
--- a/src/main/ts/ps.ts
+++ b/src/main/ts/ps.ts
@@ -172,7 +172,8 @@ const _tree = ({
   if (typeof opts === 'string' || typeof opts === 'number') {
     return _tree({opts: {pid: opts}, cb, sync})
   }
-  const handle = (all: TPsLookupEntry[]) => {
+  const onError = (err: any) => cb(err)
+  const onData = (all: TPsLookupEntry[]) => {
     if (opts === undefined) return all
 
     const {pid, recursive = false} = opts
@@ -184,10 +185,15 @@ const _tree = ({
 
   try {
     const all = _lookup({sync})
-    return sync ? handle(all) : all.then(handle)
+    return sync
+      ? onData(all)
+      : all.then(onData, (err: any) => {
+        onError(err)
+        throw err
+      })
   } catch (err) {
-    cb(err)
-    throw err
+    onError(err)
+    return Promise.reject(err)
   }
 }