diff --git a/internal/osbuild2/result.go b/internal/osbuild2/result.go
index ba95055f7..c9926f08c 100644
--- a/internal/osbuild2/result.go
+++ b/internal/osbuild2/result.go
@@ -14,6 +14,32 @@ type StageResult struct {
 	Error   string `json:"string,omitempty"`
 }
 
+// UnmarshalJSON decodes json-encoded StageResult.
+//
+// This method is here only as a workaround for the default value of the
+// success field, see the comment inside the method.
+func (sr *StageResult) UnmarshalJSON(data []byte) error {
+	// Create a StageResult-like object with the Success value set to true
+	// before json.Unmarshal is called. If the success field isn't in the
+	// input JSON, the json decoder will not touch it and thus it will still
+	// be true.
+	//
+	// The type alias is needed to prevent recursive calls of this method.
+	type stageResultAlias StageResult
+	stageResultDefault := stageResultAlias{
+		Success: true,
+	}
+
+	err := json.Unmarshal(data, &stageResultDefault)
+	if err != nil {
+		return err
+	}
+
+	*sr = StageResult(stageResultDefault)
+
+	return nil
+}
+
 type Result struct {
 	Type    string                    `json:"type"`
 	Success bool                      `json:"success"`
diff --git a/internal/osbuild2/result_test.go b/internal/osbuild2/result_test.go
index d0a454639..c49fde8bb 100644
--- a/internal/osbuild2/result_test.go
+++ b/internal/osbuild2/result_test.go
@@ -1 +1,28 @@
 package osbuild2
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStageResult_UnmarshalJSON(t *testing.T) {
+	cases := []struct {
+		input   string
+		success bool
+	}{
+		{input: `{}`, success: true},
+		{input: `{"success": true}`, success: true},
+		{input: `{"success": false}`, success: false},
+	}
+
+	for _, c := range cases {
+		t.Run(c.input, func(t *testing.T) {
+			var result StageResult
+			err := json.Unmarshal([]byte(c.input), &result)
+			assert.NoError(t, err)
+			assert.Equal(t, c.success, result.Success)
+		})
+	}
+}