diff --git a/cmd/osbuild-worker/jobimpl-koji-finalize.go b/cmd/osbuild-worker/jobimpl-koji-finalize.go
index ae7099975..7479aabc9 100644
--- a/cmd/osbuild-worker/jobimpl-koji-finalize.go
+++ b/cmd/osbuild-worker/jobimpl-koji-finalize.go
@@ -105,7 +105,7 @@ func (impl *KojiFinalizeJobImpl) Run(job worker.Job) error {
 		return err
 	}
 
-	if initArgs.KojiError != nil {
+	if initArgs.KojiError != "" {
 		failure = true
 	}
 
@@ -127,7 +127,7 @@ func (impl *KojiFinalizeJobImpl) Run(job worker.Job) error {
 		if err != nil {
 			return err
 		}
-		if !buildArgs.OSBuildOutput.Success || buildArgs.KojiError != nil {
+		if !buildArgs.OSBuildOutput.Success || buildArgs.KojiError != "" {
 			failure = true
 			break
 		}
@@ -167,9 +167,15 @@ func (impl *KojiFinalizeJobImpl) Run(job worker.Job) error {
 
 	var result worker.KojiFinalizeJobResult
 	if failure {
-		result.KojiError = impl.kojiFail(args.Server, int(initArgs.BuildID), initArgs.Token)
+		err = impl.kojiFail(args.Server, int(initArgs.BuildID), initArgs.Token)
+		if err != nil {
+			result.KojiError = err.Error()
+		}
 	} else {
-		result.KojiError = impl.kojiImport(args.Server, build, buildRoots, images, args.KojiDirectory, initArgs.Token)
+		err = impl.kojiImport(args.Server, build, buildRoots, images, args.KojiDirectory, initArgs.Token)
+		if err != nil {
+			result.KojiError = err.Error()
+		}
 	}
 
 	err = job.Update(&result)
diff --git a/cmd/osbuild-worker/jobimpl-koji-init.go b/cmd/osbuild-worker/jobimpl-koji-init.go
index ca1970db1..21d54b506 100644
--- a/cmd/osbuild-worker/jobimpl-koji-init.go
+++ b/cmd/osbuild-worker/jobimpl-koji-init.go
@@ -60,7 +60,10 @@ func (impl *KojiInitJobImpl) Run(job worker.Job) error {
 	}
 
 	var result worker.KojiInitJobResult
-	result.Token, result.BuildID, result.KojiError = impl.kojiInit(args.Server, args.Name, args.Version, args.Release)
+	result.Token, result.BuildID, err = impl.kojiInit(args.Server, args.Name, args.Version, args.Release)
+	if err != nil {
+		result.KojiError = err.Error()
+	}
 
 	err = job.Update(&result)
 	if err != nil {
diff --git a/cmd/osbuild-worker/jobimpl-osbuild-koji.go b/cmd/osbuild-worker/jobimpl-osbuild-koji.go
index 0087a2ddc..f7d2d26fb 100644
--- a/cmd/osbuild-worker/jobimpl-osbuild-koji.go
+++ b/cmd/osbuild-worker/jobimpl-osbuild-koji.go
@@ -84,7 +84,7 @@ func (impl *OSBuildKojiJobImpl) Run(job worker.Job) error {
 		return err
 	}
 
-	if initArgs.KojiError == nil {
+	if initArgs.KojiError == "" {
 		result.OSBuildOutput, err = RunOSBuild(args.Manifest, impl.Store, outputDirectory, os.Stderr)
 		if err != nil {
 			return err
@@ -95,7 +95,10 @@ func (impl *OSBuildKojiJobImpl) Run(job worker.Job) error {
 			if err != nil {
 				return err
 			}
-			result.ImageHash, result.ImageSize, result.KojiError = impl.kojiUpload(f, args.KojiServer, args.KojiDirectory, args.KojiFilename)
+			result.ImageHash, result.ImageSize, err = impl.kojiUpload(f, args.KojiServer, args.KojiDirectory, args.KojiFilename)
+			if err != nil {
+				result.KojiError = err.Error()
+			}
 		}
 	}
 
diff --git a/internal/kojiapi/server.go b/internal/kojiapi/server.go
index 09e928bd1..76b6eb336 100644
--- a/internal/kojiapi/server.go
+++ b/internal/kojiapi/server.go
@@ -190,7 +190,7 @@ func (h *apiHandlers) PostCompose(ctx echo.Context) error {
 		}
 		time.Sleep(500 * time.Millisecond)
 	}
-	if initResult.KojiError != nil {
+	if initResult.KojiError != "" {
 		return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Could not initialize build with koji: %v", initResult.KojiError))
 	}
 
@@ -224,7 +224,7 @@ func composeStatusFromJobStatus(js *worker.JobStatus, initResult *worker.KojiIni
 		return "failure"
 	}
 
-	if initResult.KojiError != nil {
+	if initResult.KojiError != "" {
 		return "failure"
 	}
 
@@ -232,7 +232,7 @@ func composeStatusFromJobStatus(js *worker.JobStatus, initResult *worker.KojiIni
 		if buildResult.OSBuildOutput != nil && !buildResult.OSBuildOutput.Success {
 			return "failure"
 		}
-		if buildResult.KojiError != nil {
+		if buildResult.KojiError != "" {
 			return "failure"
 		}
 	}
@@ -241,7 +241,7 @@ func composeStatusFromJobStatus(js *worker.JobStatus, initResult *worker.KojiIni
 		return "pending"
 	}
 
-	if result.KojiError == nil {
+	if result.KojiError == "" {
 		return "success"
 	}
 
@@ -253,7 +253,7 @@ func imageStatusFromJobStatus(js *worker.JobStatus, initResult *worker.KojiInitJ
 		return "failure"
 	}
 
-	if initResult.KojiError != nil {
+	if initResult.KojiError != "" {
 		return "failure"
 	}
 
@@ -265,7 +265,7 @@ func imageStatusFromJobStatus(js *worker.JobStatus, initResult *worker.KojiInitJ
 		return "building"
 	}
 
-	if buildResult.OSBuildOutput != nil && buildResult.OSBuildOutput.Success && buildResult.KojiError == nil {
+	if buildResult.OSBuildOutput != nil && buildResult.OSBuildOutput.Success && buildResult.KojiError == "" {
 		return "success"
 	}
 
diff --git a/internal/kojiapi/server_test.go b/internal/kojiapi/server_test.go
index f240e9507..c57b44c01 100644
--- a/internal/kojiapi/server_test.go
+++ b/internal/kojiapi/server_test.go
@@ -17,6 +17,7 @@ import (
 	"github.com/osbuild/osbuild-composer/internal/kojiapi/api"
 	distro_mock "github.com/osbuild/osbuild-composer/internal/mocks/distro"
 	rpmmd_mock "github.com/osbuild/osbuild-composer/internal/mocks/rpmmd"
+	"github.com/osbuild/osbuild-composer/internal/osbuild"
 	"github.com/osbuild/osbuild-composer/internal/test"
 	"github.com/osbuild/osbuild-composer/internal/worker"
 	"github.com/stretchr/testify/require"
@@ -55,6 +56,10 @@ func TestStatus(t *testing.T) {
 	test.TestRoute(t, handler, false, "GET", "/api/composer-koji/v1/status", ``, http.StatusOK, `{"status":"OK"}`, "message")
 }
 
+type jobResult struct {
+	Result interface{} `json:"result"`
+}
+
 func TestCompose(t *testing.T) {
 	dir, err := ioutil.TempDir("", "osbuild-composer-test-kojiapi-")
 	if err != nil {
@@ -64,139 +69,282 @@ func TestCompose(t *testing.T) {
 
 	kojiServer, workerServer := newTestKojiServer(t, dir)
 	handler := kojiServer.Handler("/api/composer-koji/v1")
-	var wg sync.WaitGroup
-	wg.Add(1)
 
-	go func() {
-		token, _, jobType, rawJob, _, err := workerServer.RequestJob(context.Background(), "x86_64", []string{"koji-init"})
-		require.NoError(t, err)
-		require.Equal(t, "koji-init", jobType)
+	type kojiCase struct {
+		initResult       worker.KojiInitJobResult
+		buildResult      worker.OSBuildKojiJobResult
+		finalizeResult   worker.KojiFinalizeJobResult
+		composeReplyCode int
+		composeReply     string
+		composeStatus    string
+	}
 
-		var initJob worker.KojiInitJob
-		err = json.Unmarshal(rawJob, &initJob)
+	var cases = []kojiCase{
+		{
+			initResult: worker.KojiInitJobResult{
+				BuildID: 42,
+				Token:   `"foobar"`,
+			},
+			buildResult: worker.OSBuildKojiJobResult{
+				Arch:      "x86_64",
+				HostOS:    "fedora-30",
+				ImageHash: "browns",
+				ImageSize: 42,
+				OSBuildOutput: &osbuild.Result{
+					Success: true,
+				},
+			},
+			composeReplyCode: http.StatusCreated,
+			composeReply:     `{"koji_build_id":42}`,
+			composeStatus: `{
+				"image_statuses": [
+					{
+						"status": "success"
+					},
+					{
+						"status": "success"
+					}
+				],
+				"koji_build_id": 42,
+				"koji_task_id": 0,
+				"status": "success"
+			}`,
+		},
+		{
+			initResult: worker.KojiInitJobResult{
+				KojiError: "failure",
+			},
+			buildResult: worker.OSBuildKojiJobResult{
+				Arch:      "x86_64",
+				HostOS:    "fedora-30",
+				ImageHash: "browns",
+				ImageSize: 42,
+				OSBuildOutput: &osbuild.Result{
+					Success: true,
+				},
+			},
+			composeReplyCode: http.StatusBadRequest,
+			composeReply:     `{"message":"Could not initialize build with koji: failure"}`,
+			composeStatus: `{
+				"image_statuses": [
+					{
+						"status": "failure"
+					},
+					{
+						"status": "failure"
+					}
+				],
+				"koji_task_id": 0,
+				"status": "failure"
+			}`,
+		},
+		{
+			initResult: worker.KojiInitJobResult{
+				BuildID: 42,
+				Token:   `"foobar"`,
+			},
+			buildResult: worker.OSBuildKojiJobResult{
+				Arch:      "x86_64",
+				HostOS:    "fedora-30",
+				ImageHash: "browns",
+				ImageSize: 42,
+				OSBuildOutput: &osbuild.Result{
+					Success: false,
+				},
+			},
+			composeReplyCode: http.StatusCreated,
+			composeReply:     `{"koji_build_id":42}`,
+			composeStatus: `{
+				"image_statuses": [
+					{
+						"status": "failure"
+					},
+					{
+						"status": "success"
+					}
+				],
+				"koji_build_id": 42,
+				"koji_task_id": 0,
+				"status": "failure"
+			}`,
+		},
+		{
+			initResult: worker.KojiInitJobResult{
+				BuildID: 42,
+				Token:   `"foobar"`,
+			},
+			buildResult: worker.OSBuildKojiJobResult{
+				Arch:      "x86_64",
+				HostOS:    "fedora-30",
+				ImageHash: "browns",
+				ImageSize: 42,
+				OSBuildOutput: &osbuild.Result{
+					Success: true,
+				},
+				KojiError: "failure",
+			},
+			composeReplyCode: http.StatusCreated,
+			composeReply:     `{"koji_build_id":42}`,
+			composeStatus: `{
+				"image_statuses": [
+					{
+						"status": "failure"
+					},
+					{
+						"status": "success"
+					}
+				],
+				"koji_build_id": 42,
+				"koji_task_id": 0,
+				"status": "failure"
+			}`,
+		},
+		{
+			initResult: worker.KojiInitJobResult{
+				BuildID: 42,
+				Token:   `"foobar"`,
+			},
+			buildResult: worker.OSBuildKojiJobResult{
+				Arch:      "x86_64",
+				HostOS:    "fedora-30",
+				ImageHash: "browns",
+				ImageSize: 42,
+				OSBuildOutput: &osbuild.Result{
+					Success: true,
+				},
+			},
+			finalizeResult: worker.KojiFinalizeJobResult{
+				KojiError: "failure",
+			},
+			composeReplyCode: http.StatusCreated,
+			composeReply:     `{"koji_build_id":42}`,
+			composeStatus: `{
+				"image_statuses": [
+					{
+						"status": "success"
+					},
+					{
+						"status": "success"
+					}
+				],
+				"koji_build_id": 42,
+				"koji_task_id": 0,
+				"status": "failure"
+			}`,
+		},
+	}
+	for _, c := range cases {
+		var wg sync.WaitGroup
+		wg.Add(1)
+
+		go func(t *testing.T, result worker.KojiInitJobResult) {
+			token, _, jobType, rawJob, _, err := workerServer.RequestJob(context.Background(), "x86_64", []string{"koji-init"})
+			require.NoError(t, err)
+			require.Equal(t, "koji-init", jobType)
+
+			var initJob worker.KojiInitJob
+			err = json.Unmarshal(rawJob, &initJob)
+			require.NoError(t, err)
+			require.Equal(t, "koji.example.com", initJob.Server)
+			require.Equal(t, "foo", initJob.Name)
+			require.Equal(t, "1", initJob.Version)
+			require.Equal(t, "2", initJob.Release)
+
+			initJobResult, err := json.Marshal(&jobResult{Result: result})
+			require.NoError(t, err)
+			test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), string(initJobResult), http.StatusOK, `{}`)
+
+			wg.Done()
+		}(t, c.initResult)
+
+		test.TestRoute(t, handler, false, "POST", "/api/composer-koji/v1/compose", `
+		{
+			"name":"foo",
+			"version":"1",
+			"release":"2",
+			"distribution":"fedora-30",
+			"image_requests": [
+				{
+					"architecture": "x86_64",
+					"image_type": "qcow2",
+					"repositories": [
+						{
+							"baseurl": "https://repo.example.com/"
+						}
+					]
+				},
+				{
+					"architecture": "x86_64",
+					"image_type": "qcow2",
+					"repositories": [
+						{
+							"baseurl": "https://repo.example.com/"
+						}
+					]
+				}
+			],
+			"koji": {
+				"server": "koji.example.com"
+			}
+		}`, c.composeReplyCode, c.composeReply, "id")
+		wg.Wait()
+
+		token, _, jobType, rawJob, _, err := workerServer.RequestJob(context.Background(), "x86_64", []string{"osbuild-koji"})
 		require.NoError(t, err)
-		require.Equal(t, "koji.example.com", initJob.Server)
-		require.Equal(t, "foo", initJob.Name)
-		require.Equal(t, "1", initJob.Version)
-		require.Equal(t, "2", initJob.Release)
+		require.Equal(t, "osbuild-koji", jobType)
+
+		var osbuildJob worker.OSBuildKojiJob
+		err = json.Unmarshal(rawJob, &osbuildJob)
+		require.NoError(t, err)
+		require.Equal(t, "koji.example.com", osbuildJob.KojiServer)
+		require.Equal(t, "test.img", osbuildJob.ImageName)
+		require.NotEmpty(t, osbuildJob.KojiDirectory)
+
+		buildJobResult, err := json.Marshal(&jobResult{Result: c.buildResult})
+		require.NoError(t, err)
+		test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), string(buildJobResult), http.StatusOK, `{}`)
+
+		token, _, jobType, rawJob, _, err = workerServer.RequestJob(context.Background(), "x86_64", []string{"osbuild-koji"})
+		require.NoError(t, err)
+		require.Equal(t, "osbuild-koji", jobType)
+
+		err = json.Unmarshal(rawJob, &osbuildJob)
+		require.NoError(t, err)
+		require.Equal(t, "koji.example.com", osbuildJob.KojiServer)
+		require.Equal(t, "test.img", osbuildJob.ImageName)
+		require.NotEmpty(t, osbuildJob.KojiDirectory)
 
 		test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), `{
-		"result": {
-			"build_id": 42,
-			"token": "foobar"
-		}
-	}`, http.StatusOK, `{}`)
-		wg.Done()
-	}()
-
-	test.TestRoute(t, handler, false, "POST", "/api/composer-koji/v1/compose", `
-	{
-		"name":"foo",
-		"version":"1",
-		"release":"2",
-		"distribution":"fedora-30",
-		"image_requests": [
-			{
-				"architecture": "x86_64",
-				"image_type": "qcow2",
-				"repositories": [
-					{
-						"baseurl": "https://repo.example.com/"
-					}
-				]
-			},
-			{
-				"architecture": "x86_64",
-				"image_type": "qcow2",
-				"repositories": [
-					{
-						"baseurl": "https://repo.example.com/"
-					}
-				]
+			"result": {
+				"arch": "x86_64",
+				"host_os": "fedora-30",
+				"image_hash": "browns",
+				"image_size": 42,
+				"osbuild_output": {
+					"success": true
+				}
 			}
-		],
-		"koji": {
-			"server": "koji.example.com"
-		}
-	}`, http.StatusCreated, `{"koji_build_id":42}`, "id")
-	wg.Wait()
+		}`, http.StatusOK, `{}`)
 
-	token, _, jobType, rawJob, _, err := workerServer.RequestJob(context.Background(), "x86_64", []string{"osbuild-koji"})
-	require.NoError(t, err)
-	require.Equal(t, "osbuild-koji", jobType)
+		token, finalizeID, jobType, rawJob, _, err := workerServer.RequestJob(context.Background(), "x86_64", []string{"koji-finalize"})
+		require.NoError(t, err)
+		require.Equal(t, "koji-finalize", jobType)
 
-	var osbuildJob worker.OSBuildKojiJob
-	err = json.Unmarshal(rawJob, &osbuildJob)
-	require.NoError(t, err)
-	require.Equal(t, "koji.example.com", osbuildJob.KojiServer)
-	require.Equal(t, "test.img", osbuildJob.ImageName)
-	require.NotEmpty(t, osbuildJob.KojiDirectory)
+		var kojiFinalizeJob worker.KojiFinalizeJob
+		err = json.Unmarshal(rawJob, &kojiFinalizeJob)
+		require.NoError(t, err)
+		require.Equal(t, "koji.example.com", kojiFinalizeJob.Server)
+		require.Equal(t, "1", kojiFinalizeJob.Version)
+		require.Equal(t, "2", kojiFinalizeJob.Release)
+		require.ElementsMatch(t, []string{"foo-1-2.x86_64.img", "foo-1-2.x86_64.img"}, kojiFinalizeJob.KojiFilenames)
+		require.NotEmpty(t, kojiFinalizeJob.KojiDirectory)
 
-	test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), `{
-		"result": {
-			"arch": "x86_64",
-			"host_os": "fedora-30",
-			"image_hash": "browns",
-			"image_size": 42,
-			"osbuild_output": {
-				"success": true
-			}
-		}
-	}`, http.StatusOK, `{}`)
+		finalizeResult, err := json.Marshal(&jobResult{Result: c.finalizeResult})
+		require.NoError(t, err)
+		test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), string(finalizeResult), http.StatusOK, `{}`)
 
-	token, _, jobType, rawJob, _, err = workerServer.RequestJob(context.Background(), "x86_64", []string{"osbuild-koji"})
-	require.NoError(t, err)
-	require.Equal(t, "osbuild-koji", jobType)
-
-	err = json.Unmarshal(rawJob, &osbuildJob)
-	require.NoError(t, err)
-	require.Equal(t, "koji.example.com", osbuildJob.KojiServer)
-	require.Equal(t, "test.img", osbuildJob.ImageName)
-	require.NotEmpty(t, osbuildJob.KojiDirectory)
-
-	test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), `{
-		"result": {
-			"arch": "x86_64",
-			"host_os": "fedora-30",
-			"image_hash": "browns",
-			"image_size": 42,
-			"osbuild_output": {
-				"success": true
-			}
-		}
-	}`, http.StatusOK, `{}`)
-
-	token, finalizeID, jobType, rawJob, _, err := workerServer.RequestJob(context.Background(), "x86_64", []string{"koji-finalize"})
-	require.NoError(t, err)
-	require.Equal(t, "koji-finalize", jobType)
-
-	var kojiFinalizeJob worker.KojiFinalizeJob
-	err = json.Unmarshal(rawJob, &kojiFinalizeJob)
-	require.NoError(t, err)
-	require.Equal(t, "koji.example.com", kojiFinalizeJob.Server)
-	require.Equal(t, "1", kojiFinalizeJob.Version)
-	require.Equal(t, "2", kojiFinalizeJob.Release)
-	require.ElementsMatch(t, []string{"foo-1-2.x86_64.img", "foo-1-2.x86_64.img"}, kojiFinalizeJob.KojiFilenames)
-	require.NotEmpty(t, kojiFinalizeJob.KojiDirectory)
-
-	test.TestRoute(t, workerServer, false, "PATCH", fmt.Sprintf("/api/worker/v1/jobs/%v", token), `{
-		"result": {
-		}
-	}`, http.StatusOK, `{}`)
-
-	test.TestRoute(t, handler, false, "GET", fmt.Sprintf("/api/composer-koji/v1/compose/%v", finalizeID), ``, http.StatusOK, `{
-		"image_statuses": [
-			{
-				"status": "success"
-			},
-			{
-				"status": "success"
-			}
-		],
-		"koji_build_id": 42,
-		"koji_task_id": 0,
-		"status": "success"
-	}`)
+		test.TestRoute(t, handler, false, "GET", fmt.Sprintf("/api/composer-koji/v1/compose/%v", finalizeID), ``, http.StatusOK, c.composeStatus)
+	}
 }
 
 func TestRequest(t *testing.T) {
diff --git a/internal/worker/json.go b/internal/worker/json.go
index 8828f316b..708a26fcb 100644
--- a/internal/worker/json.go
+++ b/internal/worker/json.go
@@ -36,7 +36,7 @@ type KojiInitJob struct {
 type KojiInitJobResult struct {
 	BuildID   uint64 `json:"build_id"`
 	Token     string `json:"token"`
-	KojiError error  `json:"koji_error"`
+	KojiError string `json:"koji_error"`
 }
 
 type OSBuildKojiJob struct {
@@ -53,7 +53,7 @@ type OSBuildKojiJobResult struct {
 	OSBuildOutput *osbuild.Result `json:"osbuild_output"`
 	ImageHash     string          `json:"image_hash"`
 	ImageSize     uint64          `json:"image_size"`
-	KojiError     error           `json:"koji_error"`
+	KojiError     string          `json:"koji_error"`
 }
 
 type KojiFinalizeJob struct {
@@ -68,7 +68,7 @@ type KojiFinalizeJob struct {
 }
 
 type KojiFinalizeJobResult struct {
-	KojiError error `json:"koji_error"`
+	KojiError string `json:"koji_error"`
 }
 
 //