diff --git a/apis/fluentbit/v1alpha2/filter_types.go b/apis/fluentbit/v1alpha2/filter_types.go
index 1a62c36cc..3e5c87cd9 100644
--- a/apis/fluentbit/v1alpha2/filter_types.go
+++ b/apis/fluentbit/v1alpha2/filter_types.go
@@ -20,13 +20,15 @@ import (
 	"bytes"
 	"crypto/md5"
 	"fmt"
+	"reflect"
+	"sort"
+	"strings"
+
 	"github.com/fluent/fluent-operator/v2/apis/fluentbit/v1alpha2/plugins"
 	"github.com/fluent/fluent-operator/v2/apis/fluentbit/v1alpha2/plugins/custom"
+	"github.com/fluent/fluent-operator/v2/apis/fluentbit/v1alpha2/plugins/filter"
 	"github.com/fluent/fluent-operator/v2/pkg/utils"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"reflect"
-	"sort"
-	"strings"
 )
 
 // EDIT THIS FILE!  THIS IS SCAFFOLDING FOR YOU TO OWN!
@@ -80,32 +82,30 @@ func (list FilterList) Load(sl plugins.SecretLoader) (string, error) {
 			if item.Spec.MatchRegex != "" {
 				buf.WriteString(fmt.Sprintf("    Match_Regex    %s\n", utils.GenerateNamespacedMatchRegExpr(item.Namespace, item.Spec.MatchRegex)))
 			}
-			for _, filter := range item.Spec.FilterItems {
-				if filter.Kubernetes != nil {
-					kubeTagPrefix := filter.Kubernetes.KubeTagPrefix
-					if kubeTagPrefix == "" {
-						kubeTagPrefix = "kube.var.log.containers."
-					}
-					filter.Kubernetes.KubeTagPrefix = fmt.Sprintf("%x.%s", md5.Sum([]byte(item.Namespace)), kubeTagPrefix)
-					if filter.Kubernetes.RegexParser != "" {
-						filter.Kubernetes.RegexParser = fmt.Sprintf("%s-%x", filter.Kubernetes.RegexParser, md5.Sum([]byte(item.Namespace)))
-					}
+
+			switch f := p.(type) {
+			case *filter.Kubernetes:
+				kubeTagPrefix := f.KubeTagPrefix
+				if kubeTagPrefix == "" {
+					kubeTagPrefix = "kube.var.log.containers."
 				}
-				if filter.Parser != nil {
-					parsers := strings.Split(filter.Parser.Parser, ",")
-					parserString := ""
-					for i := range parsers {
-						parsers[i] = strings.Trim(parsers[i], " ")
-						parsers[i] = fmt.Sprintf("%s-%x", parsers[i], md5.Sum([]byte(item.Namespace)))
-						parserString = parserString + parsers[i] + ","
-					}
-					parserString = strings.TrimSuffix(parserString, ",")
-					filter.Parser.Parser = parserString
+				f.KubeTagPrefix = fmt.Sprintf("%x.%s", md5.Sum([]byte(item.Namespace)), kubeTagPrefix)
+				if f.RegexParser != "" {
+					f.RegexParser = fmt.Sprintf("%s-%x", f.RegexParser, md5.Sum([]byte(item.Namespace)))
 				}
-				if filter.CustomPlugin != nil && filter.CustomPlugin.Config != "" {
-					filter.CustomPlugin.Config = custom.MakeCustomConfigNamespaced(filter.CustomPlugin.Config, item.Namespace)
+			case *filter.Parser:
+				parsers := strings.Split(f.Parser, ",")
+				for i := range parsers {
+					parsers[i] = strings.Trim(parsers[i], " ")
+					parsers[i] = fmt.Sprintf("%s-%x", parsers[i], md5.Sum([]byte(item.Namespace)))
+				}
+				f.Parser = strings.Join(parsers, ",")
+			case *custom.CustomPlugin:
+				if f.Config != "" {
+					f.Config = custom.MakeCustomConfigNamespaced(f.Config, item.Namespace)
 				}
 			}
+
 			kvs, err := p.Params(sl)
 			if err != nil {
 				return err
diff --git a/apis/fluentbit/v1alpha2/filter_types_test.go b/apis/fluentbit/v1alpha2/filter_types_test.go
new file mode 100644
index 000000000..6e3902ac5
--- /dev/null
+++ b/apis/fluentbit/v1alpha2/filter_types_test.go
@@ -0,0 +1,133 @@
+package v1alpha2
+
+import (
+	"testing"
+
+	"github.com/fluent/fluent-operator/v2/apis/fluentbit/v1alpha2/plugins"
+	"github.com/fluent/fluent-operator/v2/apis/fluentbit/v1alpha2/plugins/filter"
+	. "github.com/onsi/gomega"
+)
+
+func ptr[T any](v T) *T { return &v }
+
+func TestFilterList_Load(t *testing.T) {
+	testcases := []struct {
+		name     string
+		input    Filter
+		expected string
+	}{
+		{
+			name: "a single filteritem",
+			input: Filter{
+				Spec: FilterSpec{
+					FilterItems: []FilterItem{
+						FilterItem{
+							Parser: &filter.Parser{
+								KeyName: "log",
+								Parser:  "first-parser",
+							},
+						},
+					},
+				},
+			},
+			expected: `[Filter]
+    Name    parser
+    Key_Name    log
+    Parser    first-parser-d41d8cd98f00b204e9800998ecf8427e
+`,
+		},
+		{
+			name: "a single filteritem, with multiple plugins",
+			input: Filter{
+				Spec: FilterSpec{
+					FilterItems: []FilterItem{
+						FilterItem{
+							Kubernetes: &filter.Kubernetes{
+								KubeTagPrefix: "custom-tag",
+							},
+							Parser: &filter.Parser{
+								KeyName: "log",
+								Parser:  "first-parser",
+							},
+						},
+					},
+				},
+			},
+			expected: `[Filter]
+    Name    kubernetes
+    Kube_Tag_Prefix    d41d8cd98f00b204e9800998ecf8427e.custom-tag
+[Filter]
+    Name    parser
+    Key_Name    log
+    Parser    first-parser-d41d8cd98f00b204e9800998ecf8427e
+`,
+		},
+		{
+			name: "multiple filteritems",
+			input: Filter{
+				Spec: FilterSpec{
+					FilterItems: []FilterItem{
+						FilterItem{
+							Kubernetes: &filter.Kubernetes{
+								KubeTagPrefix: "custom-tag",
+							},
+							Parser: &filter.Parser{
+								KeyName: "log",
+								Parser:  "first-parser",
+							},
+						},
+						FilterItem{
+							Parser: &filter.Parser{
+								KeyName:     "msg",
+								Parser:      "second-parser",
+								ReserveData: ptr(true),
+							},
+						},
+						FilterItem{
+							Parser: &filter.Parser{
+								KeyName:     "msg",
+								Parser:      "third-parser",
+								ReserveData: ptr(true),
+							},
+						},
+					},
+				},
+			},
+			expected: `[Filter]
+    Name    kubernetes
+    Kube_Tag_Prefix    d41d8cd98f00b204e9800998ecf8427e.custom-tag
+[Filter]
+    Name    parser
+    Key_Name    log
+    Parser    first-parser-d41d8cd98f00b204e9800998ecf8427e
+[Filter]
+    Name    parser
+    Key_Name    msg
+    Parser    second-parser-d41d8cd98f00b204e9800998ecf8427e
+    Reserve_Data    true
+[Filter]
+    Name    parser
+    Key_Name    msg
+    Parser    third-parser-d41d8cd98f00b204e9800998ecf8427e
+    Reserve_Data    true
+`,
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			g := NewGomegaWithT(t)
+
+			sl := plugins.NewSecretLoader(nil, "testnamespace")
+
+			fl := FilterList{
+				Items: make([]Filter, 1),
+			}
+			fl.Items[0] = tc.input
+
+			renderedFilterList, err := fl.Load(sl)
+			g.Expect(err).NotTo(HaveOccurred())
+			g.Expect(renderedFilterList).To(Equal(tc.expected))
+		})
+	}
+}