diff --git a/.circleci/config.yml b/.circleci/config.yml
index 96845c3..fb0c53f 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -3,7 +3,8 @@ jobs:
   build:
     working_directory: ~/Clever/understream
     docker:
-    - image: circleci/node:8.11.3-stretch
+    - image: circleci/node:10.15.1-stretch
+    - image: circleci/mongo:3.2.20-jessie-ram
     environment:
       CIRCLE_ARTIFACTS: /tmp/circleci-artifacts
       CIRCLE_TEST_REPORTS: /tmp/circleci-test-results
@@ -19,3 +20,6 @@ jobs:
     - run:
         command: npm install
         name: npm install
+    - run:
+        command: make test
+        name: make test
diff --git a/Makefile b/Makefile
index ef1fc79..5b5fe3f 100644
--- a/Makefile
+++ b/Makefile
@@ -4,9 +4,9 @@
 # `make test` runs all the tests
 # `make test/each.coffee` runs just that test
 .PHONY: test test-cov
-TESTS=$(shell cd test && ls *.coffee | sed s/\.coffee$$//)
+TESTS=$(shell ls test/*.coffee | sed s/\.coffee$$//)
 LIBS=$(shell find . -regex "^./lib\/.*\.coffee\$$" | sed s/\.coffee$$/\.js/ | sed s/lib/lib-js/)
-MONGO_URL ?= localhost # needed for tests
+MONGO_URL ?= mongodb://127.0.0.1:27017 # needed for tests
 
 build: $(LIBS)
 
@@ -16,7 +16,7 @@ lib-js/%.js : lib/%.coffee
 test: $(TESTS)
 
 $(TESTS): build
-	MONGO_URL=$(MONGO_URL) DEBUG=* NODE_ENV=test node_modules/mocha/bin/mocha --timeout 60000 --bail --compilers coffee:coffee-script test/$@.coffee
+	MONGO_URL=$(MONGO_URL) DEBUG=* NODE_ENV=test node_modules/mocha/bin/mocha --timeout 60000 --bail --compilers coffee:coffee-script $@.coffee
 
 test-cov: build
 	# jscoverage only accepts directory arguments so have to rebuild everything
diff --git a/lib/helpers.coffee b/lib/helpers.coffee
index 17d3d69..5075d07 100644
--- a/lib/helpers.coffee
+++ b/lib/helpers.coffee
@@ -8,3 +8,5 @@ module.exports =
     instance instanceof EventEmitter and
     instance.pipe? and
     (instance._read? or instance.read? or instance.readable)
+
+  DEFAULT_MAX_LISTENERS: 10
diff --git a/lib/transforms/join.coffee b/lib/transforms/join.coffee
index 34243ae..1c323c0 100644
--- a/lib/transforms/join.coffee
+++ b/lib/transforms/join.coffee
@@ -106,7 +106,7 @@ class SortedMergeJoin extends Transform
   # Hack to find out if a stream has no more data. This is totally not kosher
   # since it relies on undocumented internals.
   ended = (stream) ->
-    stream._readableState.ended and _.isEmpty stream._readableState.buffer
+    stream._readableState.ended and stream._readableState.buffer.length == 0
 
   constructor: (stream_opts, {@right, @key}) ->
     super stream_opts
diff --git a/lib/understream.coffee b/lib/understream.coffee
index bc80b64..0e1d3a1 100644
--- a/lib/understream.coffee
+++ b/lib/understream.coffee
@@ -5,7 +5,7 @@ _.mixin require 'underscore.deep'
 debug  = require('debug') 'us:'
 domain = require 'domain'
 {EventEmitter} = require 'events'
-{is_readable} = require './helpers'
+{is_readable, DEFAULT_MAX_LISTENERS} = require './helpers'
 
 # Adds a listener to an EventEmitter but first bumps the max listeners limit
 # for that emitter. The limit is meant to prevent memory leaks, so this should
@@ -14,6 +14,8 @@ domain = require 'domain'
 add_listener_unsafe = (emitter, event, listener) ->
   if emitter._maxListeners?
     emitter.setMaxListeners emitter._maxListeners + 1
+  else
+    emitter._maxListeners = DEFAULT_MAX_LISTENERS + 1
   emitter.addListener event, listener
 
 # Wraps a stream's _transform method in a domain, catching any thrown errors
@@ -92,8 +94,12 @@ class ArrayStream extends Readable
   constructor: (@options, @arr, @index=0) ->
     super _(@options).extend objectMode: true
   _read: (size) =>
-    debug "_read #{size} #{JSON.stringify @arr[@index]}"
-    @push @arr[@index] # Note: push(undefined) signals the end of the stream, so this just works^tm
+    if @index > (@arr.length - 1)
+      @push null
+      return
+    data = @arr[@index]
+    debug "_read #{size} #{JSON.stringify data}"
+    @push data
     @index += 1
 
 class DevNull extends Writable
diff --git a/package.json b/package.json
index 335053c..4bc1847 100644
--- a/package.json
+++ b/package.json
@@ -1,9 +1,9 @@
 {
   "name": "understream",
-  "version": "0.10.14",
+  "version": "0.11.0",
   "description": "stream helpers",
   "engines": {
-    "node": ">=0.10.x"
+    "node": ">=10.x"
   },
   "main": "index.js",
   "scripts": {
@@ -23,12 +23,12 @@
     "underscore.deep": "^0.5.1"
   },
   "devDependencies": {
+    "JSONStream": "~0.7.1",
     "coffee-script": "~1.6.2",
-    "sinon": "~1.5.2",
     "mocha": "~1.9.0",
-    "through": "~2.3.4",
-    "mongoose": "~3.6.19",
-    "JSONStream": "~0.7.1"
+    "mongoose": "^5.7.4",
+    "sinon": "~1.5.2",
+    "through": "~2.3.4"
   },
   "publishConfig": {
     "registry": "https://registry.npmjs.org"
diff --git a/test/batch.coffee b/test/batch.coffee
index 708b963..40af0ad 100644
--- a/test/batch.coffee
+++ b/test/batch.coffee
@@ -4,7 +4,7 @@ Understream = require "#{__dirname}/../index"
 
 charRange = (start, stop) ->
   if not stop? then stop = start; start = 0
-  _(_.range(start, stop))
+  _.range(start, stop)
     .map (i) -> 'abcdefghijklmnopqrstuvwxyz'[i]
 
 describe '_.batch(n)', ->
diff --git a/test/combine.coffee b/test/combine.coffee
index dc12f75..041bee4 100644
--- a/test/combine.coffee
+++ b/test/combine.coffee
@@ -16,6 +16,10 @@ lazy_stream_from_array = (arr) ->
   i = 0
   rs._read = ->
     setImmediate =>
+      data = arr[i]
+      if data is undefined
+        @push null
+        return
       @push arr[i]
       i += 1
   rs
diff --git a/test/errors.coffee b/test/errors.coffee
index 678cf88..a0d8216 100644
--- a/test/errors.coffee
+++ b/test/errors.coffee
@@ -3,6 +3,7 @@ async  = require 'async'
 _      = require 'underscore'
 Understream = require "#{__dirname}/../index"
 {Readable} = require 'stream'
+{DEFAULT_MAX_LISTENERS} = require '../lib/helpers'
 
 # domain_thrown (0,8) vs domainThrown (0.10)
 was_thrown = (domain_err) ->
@@ -119,7 +120,7 @@ describe '_.stream error handling', ->
 
       stream = new Understream([]).stream()
       _.each ['once', 'again'], (time) -> it time, (done) ->
-        starting_max_listeners = stream._maxListeners
+        starting_max_listeners = stream._maxListeners || DEFAULT_MAX_LISTENERS
         starting_listeners = num_listeners stream
         new Understream(stream).each(-> ).run (err) ->
           assert.ifError err
diff --git a/test/join.coffee b/test/join.coffee
index 5c3a08a..8089d2e 100644
--- a/test/join.coffee
+++ b/test/join.coffee
@@ -226,7 +226,11 @@ describe '_.join', ->
         # Simulate some data being loaded after a delay
         else
           setTimeout ->
-            right.push right_input[i]
+            data = right_input[i]
+            if data?
+              right.push right_input[i]
+            else
+              right.push null
             i += 1
           , 100
 
diff --git a/test/split.coffee b/test/split.coffee
index 20e2695..7b943aa 100644
--- a/test/split.coffee
+++ b/test/split.coffee
@@ -17,7 +17,7 @@ describe '_.split', ->
     ]
     async.forEachSeries test_inputs, (test_input, cb_fe) ->
       new Understream(test_input).split("test").run (err) ->
-        assert err.message.match /non-string\/buffer chunk/
+        assert err.message.match /argument must be one of type string or Buffer/
         cb_fe()
     , done
 
diff --git a/test/wrap.coffee b/test/wrap.coffee
index 721f713..4e94e29 100644
--- a/test/wrap.coffee
+++ b/test/wrap.coffee
@@ -19,7 +19,7 @@ describe '_.stream', ->
       done()
 
   it 'wraps a mongoose stream', (done) ->
-    mongoose.connect "#{process.env.MONGO_URL}/test-understream"
+    mongoose.connect "#{process.env.MONGO_URL}/test-understream", {useNewUrlParser: true}
     Doc = mongoose.model "Doc", new mongoose.Schema { foo: String }
     input = ['a', 'b', 'c']
     async.waterfall [