diff --git a/main.go b/main.go
index 37a1a5c..7ab05aa 100644
--- a/main.go
+++ b/main.go
@@ -75,7 +75,7 @@ type apiPackage struct {
 
 func (v *apiPackage) identifier() string { return fmt.Sprintf("%s/%s", v.apiGroup, v.apiVersion) }
 
-func init() {
+func initFlags() {
 	klog.InitFlags(nil)
 	flag.Set("alsologtostderr", "true") // for klog
 	flag.Parse()
@@ -114,6 +114,8 @@ func resolveTemplateDir(dir string) error {
 func main() {
 	defer klog.Flush()
 
+	initFlags()
+
 	f, err := os.Open(*flConfig)
 	if err != nil {
 		klog.Fatalf("failed to open config file: %+v", err)
@@ -271,17 +273,21 @@ func combineAPIPackages(pkgs []*types.Package) ([]*apiPackage, error) {
 	for _, v := range pkgMap {
 		out = append(out, v)
 	}
+	sortPackages(out)
 
-	sort.SliceStable(out, func(i, j int) bool {
-		a := out[i]
-		b := out[j]
-		if a.apiGroup < b.apiGroup {
-			return true
+	return out, nil
+}
+
+// sortPackages sorts the given packages in a consistent alphabetical order.
+func sortPackages(packages []*apiPackage) {
+	sort.SliceStable(packages, func(i, j int) bool {
+		a := packages[i]
+		b := packages[j]
+		if a.apiGroup != b.apiGroup {
+			return a.apiGroup < b.apiGroup
 		}
 		return a.apiVersion < b.apiVersion
 	})
-
-	return out, nil
 }
 
 // isVendorPackage determines if package is coming from vendor/ dir.
diff --git a/main_test.go b/main_test.go
new file mode 100644
index 00000000..9c226f6
--- /dev/null
+++ b/main_test.go
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_sortPackages(t *testing.T) {
+	tests := []struct {
+		name string
+		packages []*apiPackage
+		expected []*apiPackage
+	}{
+		{
+			name: "sort by group then version",
+			packages: []*apiPackage{
+				{
+					apiGroup:   "a",
+					apiVersion: "v1",
+				},
+				{
+					apiGroup:   "c",
+					apiVersion: "v1beta1",
+				},
+				{
+					apiGroup:   "b",
+					apiVersion: "v1beta1",
+				},
+				{
+					apiGroup:   "c",
+					apiVersion: "v1",
+				},
+				{
+					apiGroup:   "b",
+					apiVersion: "v1",
+				},
+				{
+					apiGroup:   "a",
+					apiVersion: "v1beta1",
+				},
+			},
+			expected: []*apiPackage{
+				{
+					apiGroup:   "a",
+					apiVersion: "v1",
+				},
+				{
+					apiGroup:   "a",
+					apiVersion: "v1beta1",
+				},
+				{
+					apiGroup:   "b",
+					apiVersion: "v1",
+				},
+				{
+					apiGroup:   "b",
+					apiVersion: "v1beta1",
+				},
+				{
+					apiGroup:   "c",
+					apiVersion: "v1",
+				},
+				{
+					apiGroup:   "c",
+					apiVersion: "v1beta1",
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			sortPackages(tt.packages)
+			if !reflect.DeepEqual(tt.expected, tt.packages) {
+				t.Error("Unexpected packages ordering")
+			}
+		})
+	}
+}
\ No newline at end of file