diff --git a/memuvarint.go b/memuvarint.go
index 48a57f9c..fc82adce 100644
--- a/memuvarint.go
+++ b/memuvarint.go
@@ -16,6 +16,7 @@ package zap
 
 import (
 	"fmt"
+	"io"
 )
 
 type memUvarintReader struct {
@@ -50,6 +51,10 @@ func (r *memUvarintReader) ReadUvarint() (uint64, error) {
 	var S = r.S
 
 	for {
+		if C >= len(S) {
+			r.C = C
+			return 0, io.ErrUnexpectedEOF
+		}
 		b := S[C]
 		C++
 
diff --git a/memuvarint_test.go b/memuvarint_test.go
index a5b3a503..6bdd21ac 100644
--- a/memuvarint_test.go
+++ b/memuvarint_test.go
@@ -17,10 +17,25 @@ package zap
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
+	"io"
 	"math"
 	"testing"
 )
 
+func TestMemUvarintReaderReturnsUnexpectedEOFForTruncatedValue(t *testing.T) {
+	for _, input := range [][]byte{{0x80}, {0x80, 0x80}, {0xff, 0xff, 0xff}} {
+		reader := newMemUvarintReader(input)
+		_, err := reader.ReadUvarint()
+		if !errors.Is(err, io.ErrUnexpectedEOF) {
+			t.Fatalf("ReadUvarint(%x) error = %v, want %v", input, err, io.ErrUnexpectedEOF)
+		}
+		if reader.C != len(input) {
+			t.Fatalf("ReadUvarint(%x) consumed %d bytes, want %d", input, reader.C, len(input))
+		}
+	}
+}
+
 func BenchmarkUvarint(b *testing.B) {
 	n, buf := generateCommonUvarints(64, 512)