diff --git a/reaper/types.go b/reaper/types.go
index 86d0ea0..a770cf6 100644
--- a/reaper/types.go
+++ b/reaper/types.go
@@ -48,6 +48,11 @@ func (t Target) String() string {
 }
 
 func (t *Target) Set(s string) error {
+	tmp := Target(s)
+	if _, err := tmp.Selector(); err != nil {
+		return err
+	}
+
 	val := (*string)(t)
 	*val = s
 	return nil
diff --git a/reaper/types_test.go b/reaper/types_test.go
new file mode 100644
index 0000000..319a053
--- /dev/null
+++ b/reaper/types_test.go
@@ -0,0 +1,103 @@
+package reaper_test
+
+import (
+	"flag"
+	"testing"
+
+	"github.com/maxatome/go-testdeep/td"
+
+	"github.com/baez90/kreaper/reaper"
+)
+
+func TestParseTarget(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name    string
+		in      string
+		wantErr bool
+	}{
+		{
+			name:    "Empty target",
+			in:      "",
+			wantErr: true,
+		},
+		{
+			name:    "Missing value",
+			in:      "app",
+			wantErr: true,
+		},
+		{
+			name:    "Invalid separator",
+			in:      "app: prometheus",
+			wantErr: true,
+		},
+		{
+			name: "Simple target",
+			in:   "app=prometheus",
+		},
+		{
+			name: "full qualified target",
+			in:   "app.kubernetes.io/name=prometheus",
+		},
+		{
+			name:    "Invalid domain - too many path segments",
+			in:      "app.kubernetes.io/name/detailed=prometheus",
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			_, err := reaper.ParseTarget(tt.in)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseTarget() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+		})
+	}
+}
+
+func TestTargetFlag(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name    string
+		args    []string
+		want    reaper.Target
+		wantErr bool
+	}{
+		{
+			name: "Empty args",
+		},
+		{
+			name:    "Valid target",
+			args:    []string{"-target", "app.kubernetes.io/name=prometheus"},
+			want:    "app.kubernetes.io/name=prometheus",
+			wantErr: false,
+		},
+		{
+			name:    "Invalid target",
+			args:    []string{"-target", "app.kubernetes.io/name/detailed=prometheus"},
+			want:    "",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			var target reaper.Target
+			flagSet := flag.NewFlagSet(t.Name(), flag.ContinueOnError)
+			flagSet.Var(&target, "target", "")
+			if err := flagSet.Parse(tt.args); err != nil {
+				if !tt.wantErr {
+					t.Errorf("Failed to parse arguments: %v", err)
+				}
+				return
+			}
+
+			td.Cmp(t, target, tt.want)
+		})
+	}
+}