diff --git a/fluent/fluent_test.go b/fluent/fluent_test.go
index 00a6086..cdd82f2 100644
--- a/fluent/fluent_test.go
+++ b/fluent/fluent_test.go
@@ -13,7 +13,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/bmizerany/assert"
 	"github.com/tinylib/msgp/msgp"
 )
 
@@ -162,13 +161,21 @@ func (d *testDialer) waitForNextDialing(accept bool, delayReads bool) *Conn {
 	return conn
 }
 
+// asserEqual asserts that actual and expected are equivalent, and otherwise
+// marks the test as failed (t.Error). It uses reflect.DeepEqual internally.
+func assertEqual(t *testing.T, actual, expected interface{}) {
+	t.Helper()
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got: '%+v', expected: '%+v'", actual, expected)
+	}
+}
+
 // assertReceived is used below by test cases to assert the content written to a *Conn
 // matches an expected string. This is generally used in conjunction with
 // Conn.waitForNextWrite().
 func assertReceived(t *testing.T, rcv []byte, expected string) {
-	if string(rcv) != expected {
-		t.Fatalf("got %s, expect %s", string(rcv), expected)
-	}
+	t.Helper()
+	assertEqual(t, string(rcv), expected)
 }
 
 // Conn extends net.Conn to add channels used to synchronise across goroutines, eg.
@@ -272,13 +279,13 @@ func (c *Conn) Close() error {
 
 func Test_New_itShouldUseDefaultConfigValuesIfNoOtherProvided(t *testing.T) {
 	f, _ := New(Config{})
-	assert.Equal(t, f.Config.FluentPort, defaultPort)
-	assert.Equal(t, f.Config.FluentHost, defaultHost)
-	assert.Equal(t, f.Config.Timeout, defaultTimeout)
-	assert.Equal(t, f.Config.WriteTimeout, defaultWriteTimeout)
-	assert.Equal(t, f.Config.BufferLimit, defaultBufferLimit)
-	assert.Equal(t, f.Config.FluentNetwork, defaultNetwork)
-	assert.Equal(t, f.Config.FluentSocketPath, defaultSocketPath)
+	assertEqual(t, f.Config.FluentPort, defaultPort)
+	assertEqual(t, f.Config.FluentHost, defaultHost)
+	assertEqual(t, f.Config.Timeout, defaultTimeout)
+	assertEqual(t, f.Config.WriteTimeout, defaultWriteTimeout)
+	assertEqual(t, f.Config.BufferLimit, defaultBufferLimit)
+	assertEqual(t, f.Config.FluentNetwork, defaultNetwork)
+	assertEqual(t, f.Config.FluentSocketPath, defaultSocketPath)
 }
 
 func Test_New_itShouldUseUnixDomainSocketIfUnixSocketSpecified(t *testing.T) {
@@ -302,8 +309,8 @@ func Test_New_itShouldUseUnixDomainSocketIfUnixSocketSpecified(t *testing.T) {
 		return
 	}
 	defer f.Close()
-	assert.Equal(t, f.Config.FluentNetwork, network)
-	assert.Equal(t, f.Config.FluentSocketPath, socketFile)
+	assertEqual(t, f.Config.FluentNetwork, network)
+	assertEqual(t, f.Config.FluentSocketPath, socketFile)
 
 	socketFile = "/tmp/fluent-logger-golang-xxx.sock"
 	network = "unixxxx"
@@ -322,13 +329,13 @@ func Test_New_itShouldUseUnixDomainSocketIfUnixSocketSpecified(t *testing.T) {
 
 func Test_New_itShouldUseConfigValuesFromArguments(t *testing.T) {
 	f, _ := New(Config{FluentPort: 6666, FluentHost: "foobarhost"})
-	assert.Equal(t, f.Config.FluentPort, 6666)
-	assert.Equal(t, f.Config.FluentHost, "foobarhost")
+	assertEqual(t, f.Config.FluentPort, 6666)
+	assertEqual(t, f.Config.FluentHost, "foobarhost")
 }
 
 func Test_New_itShouldUseConfigValuesFromMashalAsJSONArgument(t *testing.T) {
 	f, _ := New(Config{MarshalAsJSON: true})
-	assert.Equal(t, f.Config.MarshalAsJSON, true)
+	assertEqual(t, f.Config.MarshalAsJSON, true)
 }
 
 func Test_MarshalAsMsgpack(t *testing.T) {
@@ -431,9 +438,7 @@ func TestJsonConfig(t *testing.T) {
 		t.Error(err)
 	}
 
-	if !reflect.DeepEqual(expect, got) {
-		t.Errorf("got %v, except %v", got, expect)
-	}
+	assertEqual(t, got, expect)
 }
 
 func TestPostWithTime(t *testing.T) {
@@ -643,11 +648,11 @@ func TestNoPanicOnAsyncClose(t *testing.T) {
 			if testcase.shouldError {
 				f.Close()
 			}
-			e := f.EncodeAndPostData("tag_name", time.Unix(1482493046, 0), map[string]string{"foo": "bar"})
+			err = f.EncodeAndPostData("tag_name", time.Unix(1482493046, 0), map[string]string{"foo": "bar"})
 			if testcase.shouldError {
-				assert.Equal(t, fmt.Errorf("fluent#appendBuffer: Logger already closed"), e)
+				assertEqual(t, err, fmt.Errorf("fluent#appendBuffer: Logger already closed"))
 			} else {
-				assert.Equal(t, nil, e)
+				assertEqual(t, err, nil)
 			}
 		})
 	}
@@ -755,10 +760,14 @@ func TestSyncWriteAfterCloseFails(t *testing.T) {
 		err = f.PostWithTime("tag_name", time.Unix(1482493050, 0), map[string]string{"foo": "buzz"})
 
 		// The event submission must fail,
-		assert.NotEqual(t, err, nil);
+		if err == nil {
+			t.Error("expected an error")
+		}
 
 		// and also must keep Fluentd closed.
-		assert.NotEqual(t, f.closed, false);
+		if f.closed != true {
+			t.Error("expected Fluentd to be kept closed")
+		}
 	}()
 
 	conn := d.waitForNextDialing(true, false)
diff --git a/go.mod b/go.mod
index ad74e9c..53784cd 100644
--- a/go.mod
+++ b/go.mod
@@ -2,18 +2,6 @@ module github.com/fluent/fluent-logger-golang
 
 go 1.23.5
 
-require (
-	github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869
-	github.com/tinylib/msgp v1.3.0
-)
+require github.com/tinylib/msgp v1.3.0
 
-require (
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/kr/pretty v0.3.1 // indirect
-	github.com/kr/text v0.2.0 // indirect
-	github.com/philhofer/fwd v1.1.3-0.20240916144458-20a13a1f6b7c // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/rogpeppe/go-internal v1.9.0 // indirect
-	github.com/stretchr/testify v1.10.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
-)
+require github.com/philhofer/fwd v1.1.3-0.20240916144458-20a13a1f6b7c // indirect
diff --git a/go.sum b/go.sum
index 1e41ed8..eab54d2 100644
--- a/go.sum
+++ b/go.sum
@@ -1,23 +1,4 @@
-github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869 h1:DDGfHa7BWjL4YnC6+E63dPcxHo2sUxDIu8g3QgEJdRY=
-github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869/go.mod h1:Ekp36dRnpXw/yCqJaO+ZrUyxD+3VXMFFr56k5XYrpB4=
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
-github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
-github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
-github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/philhofer/fwd v1.1.3-0.20240916144458-20a13a1f6b7c h1:dAMKvw0MlJT1GshSTtih8C2gDs04w8dReiOGXrGLNoY=
 github.com/philhofer/fwd v1.1.3-0.20240916144458-20a13a1f6b7c/go.mod h1:RqIHx9QI14HlwKwm98g9Re5prTQ6LdeRQn+gXJFxsJM=
-github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
-github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
-github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
-github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/tinylib/msgp v1.3.0 h1:ULuf7GPooDaIlbyvgAxBV/FI7ynli6LZ1/nVUNu+0ww=
 github.com/tinylib/msgp v1.3.0/go.mod h1:ykjzy2wzgrlvpDCRc4LA8UXy6D8bzMSuAF3WD57Gok0=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=