diff --git a/go.mod b/go.mod
index 6a691efac..c34a80649 100644
--- a/go.mod
+++ b/go.mod
@@ -32,7 +32,7 @@ require (
 	github.com/santhosh-tekuri/jsonschema/v6 v6.0.3
 	github.com/spf13/cobra v1.10.2
 	github.com/spf13/pflag v1.0.10
-	github.com/stretchr/testify v1.12.0
+	github.com/stretchr/testify v1.12.1
 	github.com/tetratelabs/wazero v1.12.0
 	go.yaml.in/yaml/v3 v3.0.5
 	golang.org/x/crypto v0.55.0
diff --git a/go.sum b/go.sum
index 54d14492a..bfac195f1 100644
--- a/go.sum
+++ b/go.sum
@@ -307,8 +307,8 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.12.0 h1:K6Mr6jO9JICuend/5xzTM03ydSV3vdNRYAdPSukj8uI=
-github.com/stretchr/testify v1.12.0/go.mod h1:bOYBZb5qJ00vPzWfIqBUZPaxK8jWiXc6d3ErP4Ca9Gw=
+github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
+github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
 github.com/tetratelabs/wabin v0.0.0-20230304001439-f6f874872834 h1:ZF+QBjOI+tILZjBaFj3HgFonKXUcwgJ4djLb6i42S3Q=
 github.com/tetratelabs/wabin v0.0.0-20230304001439-f6f874872834/go.mod h1:m9ymHTgNSEjuxvw8E7WWe4Pl4hZQHXONY8wE6dMLaRk=
 github.com/tetratelabs/wazero v1.12.0 h1:DuWcpNu/FzgEXgGBDp8J1Spc+CWOvvtvVyjKlaZopYU=
diff --git a/internal/chart/v3/loader/load.go b/internal/chart/v3/loader/load.go
index 48f346ccf..0ff040eae 100644
--- a/internal/chart/v3/loader/load.go
+++ b/internal/chart/v3/loader/load.go
@@ -183,8 +183,20 @@ func LoadFiles(files []*archive.BufferedFile) (*chart.Chart, error) {
 // The reader is expected to contain one or more YAML documents, the values of which are merged.
 // And the values can be either a chart's default values or user-supplied values.
 func LoadValues(data io.Reader) (map[string]any, error) {
+	// Read fully first. YAMLReader/LineReader can drop a final unterminated
+	// line when its length is an exact multiple of bufio.Reader's default
+	// buffer (4096). Appending a trailing newline avoids that case.
+	// See https://github.com/helm/helm/issues/32506
+	b, err := io.ReadAll(data)
+	if err != nil {
+		return nil, err
+	}
+	if len(b) > 0 && b[len(b)-1] != '\n' {
+		b = append(b, '\n')
+	}
+
 	values := map[string]any{}
-	reader := utilyaml.NewYAMLReader(bufio.NewReader(data))
+	reader := utilyaml.NewYAMLReader(bufio.NewReader(bytes.NewReader(b)))
 	for {
 		currentMap := map[string]any{}
 		raw, err := reader.Read()
diff --git a/internal/chart/v3/loader/load_test.go b/internal/chart/v3/loader/load_test.go
index dd5fdc8db..e34364f39 100644
--- a/internal/chart/v3/loader/load_test.go
+++ b/internal/chart/v3/loader/load_test.go
@@ -21,6 +21,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"os"
@@ -419,6 +420,33 @@ foo:
 	}
 }
 
+func TestLoadValuesEOFBoundary(t *testing.T) {
+	// Reproduces #32506: a single logical line whose length is a multiple of
+	// bufio's default buffer (4096) and has no trailing newline used to be
+	// dropped entirely by YAMLReader, yielding empty values.
+	// Also cover 8192 (2x buffer) so we do not only hit the single-buffer case.
+	for _, size := range []int{4096, 8192} {
+		t.Run(fmt.Sprintf("size_%d", size), func(t *testing.T) {
+			prefix := []byte(`{"foo":"`)
+			suffix := []byte(`"}`)
+			pad := size - len(prefix) - len(suffix)
+			data := make([]byte, 0, size)
+			data = append(data, prefix...)
+			data = append(data, bytes.Repeat([]byte("x"), pad)...)
+			data = append(data, suffix...)
+			if len(data) != size {
+				t.Fatalf("test setup: want data length %d, got %d", size, len(data))
+			}
+
+			values, err := LoadValues(bytes.NewReader(data))
+			require.NoError(t, err)
+			assert.Equal(t, map[string]any{
+				"foo": string(bytes.Repeat([]byte("x"), pad)),
+			}, values)
+		})
+	}
+}
+
 func TestMergeValuesV3(t *testing.T) {
 	nestedMap := map[string]any{
 		"foo": "bar",
diff --git a/pkg/action/package_test.go b/pkg/action/package_test.go
index 421f34b33..2b359fa52 100644
--- a/pkg/action/package_test.go
+++ b/pkg/action/package_test.go
@@ -17,9 +17,14 @@ limitations under the License.
 package action
 
 import (
+	"archive/tar"
+	"compress/gzip"
+	"errors"
+	"io"
 	"os"
 	"path"
 	"testing"
+	"time"
 
 	"github.com/Masterminds/semver/v3"
 	"github.com/stretchr/testify/assert"
@@ -144,3 +149,60 @@ func TestRun(t *testing.T) {
 	require.Equal(t, "empty-0.1.0.tgz", filename)
 	require.NoError(t, os.Remove(filename))
 }
+
+// TestRunWithSourceDateEpochStampsLockGenerated verifies that packaging a chart
+// that has a Chart.lock stamps both the tar entry modtime and the marshaled
+// generated: field in Chart.lock to the given epoch.
+//
+// This guards against the normalization regression where a caller supplying a
+// local-timezone or sub-second time.Time would produce a non-reproducible
+// generated: value even when the same SOURCE_DATE_EPOCH is used on different
+// machines.
+func TestRunWithSourceDateEpochStampsLockGenerated(t *testing.T) {
+	// Use a non-local, non-UTC timezone and sub-second precision to confirm
+	// normalization: without UTC().Truncate(time.Second) the generated: field
+	// would contain a timezone offset or fractional seconds.
+	loc := time.FixedZone("UTC+3", 3*60*60)
+	rawEpoch := time.Unix(1700000000, 123456789).In(loc)
+	epoch := rawEpoch.UTC().Truncate(time.Second)
+
+	client := NewPackage()
+	client.SourceDateEpoch = &rawEpoch
+
+	filename, err := client.Run("testdata/charts/chart-with-lock", nil)
+	require.NoError(t, err)
+	t.Cleanup(func() { os.Remove(filename) })
+
+	f, err := os.Open(filename)
+	require.NoError(t, err)
+	defer f.Close()
+
+	gr, err := gzip.NewReader(f)
+	require.NoError(t, err)
+	defer gr.Close()
+
+	const wantPath = "chart-with-lock/Chart.lock"
+	found := false
+	tr := tar.NewReader(gr)
+	for {
+		hdr, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		require.NoError(t, err)
+		if hdr.Name != wantPath {
+			continue
+		}
+		found = true
+		require.True(t, epoch.Equal(hdr.ModTime),
+			"Chart.lock tar modtime: got %v, want %v", hdr.ModTime, epoch)
+
+		raw, err := io.ReadAll(tr)
+		require.NoError(t, err)
+		wantGenerated := epoch.Format(time.RFC3339)
+		require.Contains(t, string(raw), wantGenerated,
+			"Chart.lock generated: field should contain normalized UTC timestamp")
+		break
+	}
+	require.True(t, found, "expected archive to contain %q entry", wantPath)
+}
diff --git a/pkg/action/testdata/charts/chart-with-lock/Chart.lock b/pkg/action/testdata/charts/chart-with-lock/Chart.lock
new file mode 100644
index 000000000..824df0a40
--- /dev/null
+++ b/pkg/action/testdata/charts/chart-with-lock/Chart.lock
@@ -0,0 +1,3 @@
+dependencies: []
+digest: sha256:0000000000000000000000000000000000000000000000000000000000000
+generated: "2016-01-01T00:00:00Z"
diff --git a/pkg/action/testdata/charts/chart-with-lock/Chart.yaml b/pkg/action/testdata/charts/chart-with-lock/Chart.yaml
new file mode 100644
index 000000000..2cb1b3557
--- /dev/null
+++ b/pkg/action/testdata/charts/chart-with-lock/Chart.yaml
@@ -0,0 +1,4 @@
+apiVersion: v2
+name: chart-with-lock
+version: 0.1.0
+description: Test chart with a Chart.lock, used to verify SourceDateEpoch stamping
diff --git a/pkg/chart/v2/chart.go b/pkg/chart/v2/chart.go
index 9772754ce..ccfe84f51 100644
--- a/pkg/chart/v2/chart.go
+++ b/pkg/chart/v2/chart.go
@@ -177,34 +177,41 @@ func (ch *Chart) CRDObjects() []CRD {
 	return crds
 }
 
-// StampModTimes sets timestamps on the chart (and dependencies) to epoch.
-// This is used for reproducible builds via SOURCE_DATE_EPOCH.
-func (ch *Chart) StampModTimes(epoch time.Time) {
-	ch.ModTime = epoch
+// StampModTimes sets timestamps on the chart (and dependencies) to t,
+// normalized to UTC and truncated to whole seconds.
+//
+// Normalization is required because Chart.lock's generated: field is written
+// by yaml.Marshal from Lock.Generated. Without UTC/truncate, a caller
+// supplying a local-zone or sub-second time.Time produces a generated: value
+// with a timezone offset or fractional seconds, making the lock file content
+// non-reproducible across machines even when the same SOURCE_DATE_EPOCH is used.
+func (ch *Chart) StampModTimes(t time.Time) {
+	t = t.UTC().Truncate(time.Second)
+	ch.ModTime = t
 	if len(ch.Schema) > 0 {
-		ch.SchemaModTime = epoch
+		ch.SchemaModTime = t
 	}
 	if ch.Lock != nil {
-		ch.Lock.Generated = epoch
+		ch.Lock.Generated = t
 	}
 
 	for _, f := range ch.Raw {
 		if f != nil {
-			f.ModTime = epoch
+			f.ModTime = t
 		}
 	}
 	for _, f := range ch.Templates {
 		if f != nil {
-			f.ModTime = epoch
+			f.ModTime = t
 		}
 	}
 	for _, f := range ch.Files {
 		if f != nil {
-			f.ModTime = epoch
+			f.ModTime = t
 		}
 	}
 	for _, dep := range ch.Dependencies() {
-		dep.StampModTimes(epoch)
+		dep.StampModTimes(t)
 	}
 }
 
diff --git a/pkg/chart/v2/loader/load.go b/pkg/chart/v2/loader/load.go
index 28115d062..d7b125b9b 100644
--- a/pkg/chart/v2/loader/load.go
+++ b/pkg/chart/v2/loader/load.go
@@ -210,8 +210,20 @@ func LoadFiles(files []*archive.BufferedFile) (*chart.Chart, error) {
 // The reader is expected to contain one or more YAML documents, the values of which are merged.
 // And the values can be either a chart's default values or user-supplied values.
 func LoadValues(data io.Reader) (map[string]any, error) {
+	// Read fully first. YAMLReader/LineReader can drop a final unterminated
+	// line when its length is an exact multiple of bufio.Reader's default
+	// buffer (4096). Appending a trailing newline avoids that case.
+	// See https://github.com/helm/helm/issues/32506
+	b, err := io.ReadAll(data)
+	if err != nil {
+		return nil, err
+	}
+	if len(b) > 0 && b[len(b)-1] != '\n' {
+		b = append(b, '\n')
+	}
+
 	values := map[string]any{}
-	reader := utilyaml.NewYAMLReader(bufio.NewReader(data))
+	reader := utilyaml.NewYAMLReader(bufio.NewReader(bytes.NewReader(b)))
 	for {
 		currentMap := map[string]any{}
 		raw, err := reader.Read()
diff --git a/pkg/chart/v2/loader/load_test.go b/pkg/chart/v2/loader/load_test.go
index 8bf254321..ae1da1130 100644
--- a/pkg/chart/v2/loader/load_test.go
+++ b/pkg/chart/v2/loader/load_test.go
@@ -21,6 +21,7 @@ import (
 	"bytes"
 	"compress/gzip"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"os"
@@ -463,6 +464,33 @@ foo:
 	}
 }
 
+func TestLoadValuesEOFBoundary(t *testing.T) {
+	// Reproduces #32506: a single logical line whose length is a multiple of
+	// bufio's default buffer (4096) and has no trailing newline used to be
+	// dropped entirely by YAMLReader, yielding empty values.
+	// Also cover 8192 (2x buffer) so we do not only hit the single-buffer case.
+	for _, size := range []int{4096, 8192} {
+		t.Run(fmt.Sprintf("size_%d", size), func(t *testing.T) {
+			prefix := []byte(`{"foo":"`)
+			suffix := []byte(`"}`)
+			pad := size - len(prefix) - len(suffix)
+			data := make([]byte, 0, size)
+			data = append(data, prefix...)
+			data = append(data, bytes.Repeat([]byte("x"), pad)...)
+			data = append(data, suffix...)
+			if len(data) != size {
+				t.Fatalf("test setup: want data length %d, got %d", size, len(data))
+			}
+
+			values, err := LoadValues(bytes.NewReader(data))
+			require.NoError(t, err)
+			assert.Equal(t, map[string]any{
+				"foo": string(bytes.Repeat([]byte("x"), pad)),
+			}, values)
+		})
+	}
+}
+
 func TestMergeValuesV2(t *testing.T) {
 	nestedMap := map[string]any{
 		"foo": "bar",