diff --git a/qlog/frame.go b/qlog/frame.go
index 9926cf2e3..b820997bb 100644
--- a/qlog/frame.go
+++ b/qlog/frame.go
@@ -236,8 +236,12 @@ func marshalConnectionCloseFrame(enc *gojay.Encoder, f *wire.ConnectionCloseFram
 	}
 	enc.StringKey("frame_type", "connection_close")
 	enc.StringKey("error_space", errorSpace)
-	enc.Int64Key("error_code", int64(f.ErrorCode))
-	enc.Int64Key("raw_error_code", int64(f.ErrorCode))
+	if errName := transportError(f.ErrorCode).String(); len(errName) > 0 {
+		enc.StringKey("error_code", errName)
+	} else {
+		enc.Uint64Key("error_code", uint64(f.ErrorCode))
+	}
+	enc.Uint64Key("raw_error_code", uint64(f.ErrorCode))
 	enc.StringKey("reason", f.ReasonPhrase)
 }
 
diff --git a/qlog/frame_test.go b/qlog/frame_test.go
index 79d9a8543..a3bfd93ba 100644
--- a/qlog/frame_test.go
+++ b/qlog/frame_test.go
@@ -5,6 +5,8 @@ import (
 	"encoding/json"
 	"time"
 
+	"github.com/lucas-clemente/quic-go/internal/qerr"
+
 	"github.com/francoispqt/gojay"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
@@ -325,14 +327,14 @@ var _ = Describe("Frames", func() {
 	It("marshals CONNECTION_CLOSE frames, for transport error codes", func() {
 		check(
 			&wire.ConnectionCloseFrame{
-				ErrorCode:    1337,
+				ErrorCode:    qerr.FlowControlError,
 				ReasonPhrase: "lorem ipsum",
 			},
 			map[string]interface{}{
 				"frame_type":     "connection_close",
 				"error_space":    "transport",
-				"error_code":     1337,
-				"raw_error_code": 1337,
+				"error_code":     "flow_control_error",
+				"raw_error_code": int(qerr.FlowControlError),
 				"reason":         "lorem ipsum",
 			},
 		)
diff --git a/qlog/types.go b/qlog/types.go
index baffaedd0..a8dd74045 100644
--- a/qlog/types.go
+++ b/qlog/types.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/qerr"
 )
 
 type owner uint8
@@ -264,3 +265,40 @@ func (r PacketDropReason) String() string {
 		panic("unknown packet drop reason")
 	}
 }
+
+type transportError uint64
+
+func (e transportError) String() string {
+	switch qerr.ErrorCode(e) {
+	case qerr.NoError:
+		return "no_error"
+	case qerr.InternalError:
+		return "internal_error"
+	case qerr.ServerBusy:
+		return "server_busy"
+	case qerr.FlowControlError:
+		return "flow_control_error"
+	case qerr.StreamLimitError:
+		return "stream_limit_error"
+	case qerr.StreamStateError:
+		return "stream_state_error"
+	case qerr.FinalSizeError:
+		return "final_size_error"
+	case qerr.FrameEncodingError:
+		return "frame_encoding_error"
+	case qerr.TransportParameterError:
+		return "transport_parameter_error"
+	case qerr.ConnectionIDLimitError:
+		return "connection_id_limit_error"
+	case qerr.ProtocolViolation:
+		return "protocol_violation"
+	case qerr.InvalidToken:
+		return "invalid_token"
+	case qerr.ApplicationError:
+		return "application_error"
+	case qerr.CryptoBufferExceeded:
+		return "crypto_buffer_exceeded"
+	default:
+		return ""
+	}
+}
diff --git a/qlog/types_test.go b/qlog/types_test.go
index 9d0b92609..df2ea0939 100644
--- a/qlog/types_test.go
+++ b/qlog/types_test.go
@@ -1,7 +1,16 @@
 package qlog
 
 import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"path"
+	"runtime"
+	"strconv"
+
 	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/qerr"
+
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 )
@@ -56,4 +65,42 @@ var _ = Describe("Types", func() {
 		Expect(PacketDropDOSPrevention.String()).To(Equal("dos_prevention"))
 		Expect(PacketDropUnsupportedVersion.String()).To(Equal("unsupported_version"))
 	})
+
+	Context("transport errors", func() {
+		It("has a string representation for every error code", func() {
+			// We parse the error code file, extract all constants, and verify that
+			// each of them has a string version. Go FTW!
+			_, thisfile, _, ok := runtime.Caller(0)
+			if !ok {
+				panic("Failed to get current frame")
+			}
+			filename := path.Join(path.Dir(thisfile), "../internal/qerr/error_codes.go")
+			fileAst, err := parser.ParseFile(token.NewFileSet(), filename, nil, 0)
+			Expect(err).NotTo(HaveOccurred())
+			constSpecs := fileAst.Decls[2].(*ast.GenDecl).Specs
+			Expect(len(constSpecs)).To(BeNumerically(">", 4)) // at time of writing
+			for _, c := range constSpecs {
+				valString := c.(*ast.ValueSpec).Values[0].(*ast.BasicLit).Value
+				val, err := strconv.ParseInt(valString, 0, 64)
+				Expect(err).NotTo(HaveOccurred())
+				Expect(transportError(val).String()).ToNot(BeEmpty())
+			}
+		})
+
+		It("has a string representation for transport errors", func() {
+			Expect(transportError(qerr.NoError).String()).To(Equal("no_error"))
+			Expect(transportError(qerr.InternalError).String()).To(Equal("internal_error"))
+			Expect(transportError(qerr.ServerBusy).String()).To(Equal("server_busy"))
+			Expect(transportError(qerr.FlowControlError).String()).To(Equal("flow_control_error"))
+			Expect(transportError(qerr.StreamLimitError).String()).To(Equal("stream_limit_error"))
+			Expect(transportError(qerr.StreamStateError).String()).To(Equal("stream_state_error"))
+			Expect(transportError(qerr.FrameEncodingError).String()).To(Equal("frame_encoding_error"))
+			Expect(transportError(qerr.ConnectionIDLimitError).String()).To(Equal("connection_id_limit_error"))
+			Expect(transportError(qerr.ProtocolViolation).String()).To(Equal("protocol_violation"))
+			Expect(transportError(qerr.InvalidToken).String()).To(Equal("invalid_token"))
+			Expect(transportError(qerr.ApplicationError).String()).To(Equal("application_error"))
+			Expect(transportError(qerr.CryptoBufferExceeded).String()).To(Equal("crypto_buffer_exceeded"))
+			Expect(transportError(1337).String()).To(BeEmpty())
+		})
+	})
 })