diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fcf12a14..03f2f1e8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ ruby-head, '3.2', '3.1', '3.0', '2.7', '2.6', '2.5', '2.4', '2.3', '2.2', truffleruby ]
+        ruby: [ ruby-head, '3.2', '3.1', '3.0', '2.7', truffleruby ]
     steps:
       - name: Checkout
         uses: actions/checkout@v2
diff --git a/stackprof.gemspec b/stackprof.gemspec
index 2964d4c2..4f6b34cf 100644
--- a/stackprof.gemspec
+++ b/stackprof.gemspec
@@ -29,6 +29,5 @@ Gem::Specification.new do |s|
   s.license = 'MIT'
 
   s.add_development_dependency 'rake-compiler', '~> 0.9'
-  s.add_development_dependency 'mocha', '~> 0.14'
   s.add_development_dependency 'minitest', '~> 5.0'
 end
diff --git a/test/test_middleware.rb b/test/test_middleware.rb
index afb335aa..b92e1ce1 100644
--- a/test/test_middleware.rb
+++ b/test/test_middleware.rb
@@ -2,7 +2,7 @@
 require 'stackprof'
 require 'stackprof/middleware'
 require 'minitest/autorun'
-require 'mocha/setup'
+require 'tmpdir'
 
 class StackProf::MiddlewareTest < MiniTest::Test
 
@@ -19,23 +19,36 @@ def test_path_custom
   end
 
   def test_save_default
-    StackProf::Middleware.new(Object.new)
-
-    StackProf.stubs(:results).returns({ mode: 'foo' })
-    FileUtils.expects(:mkdir_p).with('tmp/')
-    File.expects(:open).with(regexp_matches(/^tmp\/stackprof-foo/), 'wb')
-
-    StackProf::Middleware.save
+    middleware = StackProf::Middleware.new(->(env) { 100.times { Object.new } },
+                                          save_every: 1,
+                                          enabled: true)
+    Dir.mktmpdir do |dir|
+      Dir.chdir(dir) { middleware.call({}) }
+      dir = File.join(dir, "tmp")
+      assert File.directory? dir
+      profile = Dir.entries(dir).reject { |x| File.directory?(x) }.first
+      assert profile
+      assert_equal "stackprof", profile.split("-")[0]
+      assert_equal "cpu", profile.split("-")[1]
+      assert_equal Process.pid.to_s, profile.split("-")[2]
+    end
   end
 
   def test_save_custom
-    StackProf::Middleware.new(Object.new, { path: 'foo/' })
-
-    StackProf.stubs(:results).returns({ mode: 'foo' })
-    FileUtils.expects(:mkdir_p).with('foo/')
-    File.expects(:open).with(regexp_matches(/^foo\/stackprof-foo/), 'wb')
-
-    StackProf::Middleware.save
+    middleware = StackProf::Middleware.new(->(env) { 100.times { Object.new } },
+                                          path: "foo/",
+                                          save_every: 1,
+                                          enabled: true)
+    Dir.mktmpdir do |dir|
+      Dir.chdir(dir) { middleware.call({}) }
+      dir = File.join(dir, "foo")
+      assert File.directory? dir
+      profile = Dir.entries(dir).reject { |x| File.directory?(x) }.first
+      assert profile
+      assert_equal "stackprof", profile.split("-")[0]
+      assert_equal "cpu", profile.split("-")[1]
+      assert_equal Process.pid.to_s, profile.split("-")[2]
+    end
   end
 
   def test_enabled_should_use_a_proc_if_passed
@@ -70,4 +83,4 @@ def test_metadata
     StackProf::Middleware.new(Object.new, metadata: metadata)
     assert_equal metadata, StackProf::Middleware.metadata
   end
-end
+end unless RUBY_ENGINE == 'truffleruby'
diff --git a/test/test_stackprof.rb b/test/test_stackprof.rb
index 2aedc0bc..dc9948be 100644
--- a/test/test_stackprof.rb
+++ b/test/test_stackprof.rb
@@ -93,6 +93,7 @@ def test_cputime
   end
 
   def test_walltime
+    GC.disable
     profile = StackProf.run(mode: :wall) do
       idle
     end
@@ -104,6 +105,8 @@ def test_walltime
       assert_equal "StackProfTest#idle", frame[:name]
     end
     assert_in_delta 200, frame[:samples], 25
+  ensure
+    GC.enable
   end
 
   def test_custom
@@ -241,8 +244,12 @@ def test_gc
     assert marking_frame
     assert sweeping_frame
 
-    assert_equal gc_frame[:total_samples], profile[:gc_samples]
-    assert_equal profile[:gc_samples], [gc_frame, marking_frame, sweeping_frame].map{|x| x[:samples] }.inject(:+)
+    # We can't guarantee a certain number of GCs to run, so just assert
+    # that it's within some kind of delta
+    assert_in_delta gc_frame[:total_samples], profile[:gc_samples], 2
+
+    # Lazy marking / sweeping can cause this math to not add up, so also use a delta
+    assert_in_delta profile[:gc_samples], [gc_frame, marking_frame, sweeping_frame].map{|x| x[:samples] }.inject(:+), 2
 
     assert_operator profile[:gc_samples], :>, 0
     assert_operator profile[:missed_samples], :<=, 25