diff --git a/.github/env b/.github/env
index 9d79b174f..9a0c1ef4c 100644
--- a/.github/env
+++ b/.github/env
@@ -1,2 +1,2 @@
-GOLANG_VERSION=1.25
-GOLANGCI_LINT_VERSION=v2.5.0
+GOLANG_VERSION=1.26
+GOLANGCI_LINT_VERSION=v2.12.2
diff --git a/go.mod b/go.mod
index da53bf246..bf14f99b4 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module helm.sh/helm/v3
 
-go 1.25.0
+go 1.26.0
 
 require (
 	github.com/AdaLogics/go-fuzz-headers v0.0.0-20230811130428-ced1acdcaa24
diff --git a/pkg/chartutil/jsonschema.go b/pkg/chartutil/jsonschema.go
index 632e6dfd1..3718cf37a 100644
--- a/pkg/chartutil/jsonschema.go
+++ b/pkg/chartutil/jsonschema.go
@@ -78,7 +78,7 @@ func ValidateAgainstSchema(chrt *chart.Chart, values map[string]interface{}) err
 
 		err := ValidateAgainstSingleSchema(values, chrt.Schema)
 		if err != nil {
-			sb.WriteString(fmt.Sprintf("%s:\n", chrt.Name()))
+			fmt.Fprintf(&sb, "%s:\n", chrt.Name())
 			sb.WriteString(err.Error())
 		}
 	}
@@ -92,10 +92,10 @@ func ValidateAgainstSchema(chrt *chart.Chart, values map[string]interface{}) err
 
 		subchartValues, ok := raw.(map[string]any)
 		if !ok {
-			sb.WriteString(fmt.Sprintf(
+			fmt.Fprintf(&sb,
 				"%s:\ninvalid type for values: expected object (map), got %T\n",
 				subchart.Name(), raw,
-			))
+			)
 			continue
 		}
 		if err := ValidateAgainstSchema(subchart, subchartValues); err != nil {