diff --git a/cmd/pr-size-labeler-action/main.go b/cmd/pr-size-labeler-action/main.go
index c9b8d32..6271731 100644
--- a/cmd/pr-size-labeler-action/main.go
+++ b/cmd/pr-size-labeler-action/main.go
@@ -41,7 +41,6 @@ func (EnvArgs) Version() string {
 // Constants for default configuration and event names.
 const (
 	DefaultConfigPath = ".github/pull-request-size.yml"
-	EventPullRequest  = "pull_request"
 	ParamNameFiles    = "files"
 	ParamNameDiff     = "diff"
 )
@@ -116,7 +115,7 @@ func main() {
 	var args EnvArgs
 	arg.MustParse(&args)
 
-	if !isValidEvent(args.EventName) || !isValidRepoFormat(args.RepoName) {
+	if !isValidGitHubEventType(args.EventName) || !isValidRepoFormat(args.RepoName) {
 		return
 	}
 
@@ -138,13 +137,19 @@ func main() {
 	prProcessor.ProcessPullRequest()
 }
 
-// isValidEvent checks if the event name is a valid pull request event.
-func isValidEvent(eventName string) bool {
-	if eventName != EventPullRequest {
-		fmt.Println("Event is not a pull request, doing nothing")
-		return false
+// isValidGitHubEventType checks if the event name is a valid pull request event.
+func isValidGitHubEventType(eventName string) bool {
+	allowedEvents := map[string]bool{
+		"pull_request":        true,
+		"pull_request_target": true,
 	}
-	return true
+
+	if allowedEvents[strings.ToLower(eventName)] {
+		return true
+	}
+
+	fmt.Println("Event is not a valid pull request event, doing nothing")
+	return false
 }
 
 // isValidRepoFormat checks if the repository name follows the 'owner/repository' format.
diff --git a/cmd/pr-size-labeler-action/main_test.go b/cmd/pr-size-labeler-action/main_test.go
index 53a55f7..4882ace 100644
--- a/cmd/pr-size-labeler-action/main_test.go
+++ b/cmd/pr-size-labeler-action/main_test.go
@@ -75,6 +75,33 @@ func TestCalculateSizeAndDiff(t *testing.T) {
 	}
 }
 
+func TestIsValidGitHubEventType(t *testing.T) {
+	tests := []struct {
+		name      string
+		eventName string
+		want      bool
+	}{
+		{"Valid Event pull_request", "pull_request", true},
+		{"Valid Event pull_request_target", "pull_request_target", true},
+		{"Invalid Event empty", "", false},
+		{"Invalid Event random string", "random_event", false},
+		{"Invalid Event issue", "issue", false},
+		{"Invalid Event commit", "commit", false},
+		{"Invalid Event push", "push", false},
+		{"Invalid Event merge", "merge", false},
+		{"Invalid Event null", "null", false},
+		{"Invalid Event pull_request_closed", "pull_request_closed", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isValidGitHubEventType(tt.eventName); got != tt.want {
+				t.Errorf("isValidGitHubEventType(%v) = %v, want %v", tt.eventName, got, tt.want)
+			}
+		})
+	}
+}
+
 func TestGetSize(t *testing.T) {
 	// Define configuration entries for clarity
 	xsConfig := ConfigEntry{"xs", 10, 1, []string{"size/xs"}}