diff --git a/internal/chart/v3/lint/rules/template.go b/internal/chart/v3/lint/rules/template.go
index d4c62839f..204966364 100644
--- a/internal/chart/v3/lint/rules/template.go
+++ b/internal/chart/v3/lint/rules/template.go
@@ -126,7 +126,7 @@ func TemplatesWithSkipSchemaValidation(linter *support.Linter, values map[string
 		linter.RunLinterRule(support.ErrorSev, fpath, validateAllowedExtension(fileName))
 
 		// We only apply the following lint rules to yaml files
-		if filepath.Ext(fileName) != ".yaml" || filepath.Ext(fileName) == ".yml" {
+		if !isYamlFileExtension(fileName) {
 			continue
 		}
 
@@ -335,6 +335,11 @@ func validateListAnnotations(yamlStruct *k8sYamlStruct, manifest string) error {
 	return nil
 }
 
+func isYamlFileExtension(fileName string) bool {
+	ext := strings.ToLower(filepath.Ext(fileName))
+	return ext == ".yaml" || ext == ".yml"
+}
+
 // k8sYamlStruct stubs a Kubernetes YAML file.
 type k8sYamlStruct struct {
 	APIVersion string `json:"apiVersion"`
diff --git a/pkg/chart/v2/lint/rules/template.go b/pkg/chart/v2/lint/rules/template.go
index 5c84d0f68..c3cded5d3 100644
--- a/pkg/chart/v2/lint/rules/template.go
+++ b/pkg/chart/v2/lint/rules/template.go
@@ -126,7 +126,7 @@ func TemplatesWithSkipSchemaValidation(linter *support.Linter, values map[string
 		linter.RunLinterRule(support.ErrorSev, fpath, validateAllowedExtension(fileName))
 
 		// We only apply the following lint rules to yaml files
-		if filepath.Ext(fileName) != ".yaml" || filepath.Ext(fileName) == ".yml" {
+		if !isYamlFileExtension(fileName) {
 			continue
 		}
 
@@ -335,6 +335,11 @@ func validateListAnnotations(yamlStruct *k8sYamlStruct, manifest string) error {
 	return nil
 }
 
+func isYamlFileExtension(fileName string) bool {
+	ext := strings.ToLower(filepath.Ext(fileName))
+	return ext == ".yaml" || ext == ".yml"
+}
+
 // k8sYamlStruct stubs a Kubernetes YAML file.
 type k8sYamlStruct struct {
 	APIVersion string `json:"apiVersion"`