diff --git a/ber.go b/ber.go
index 95755fe..2ffb663 100644
--- a/ber.go
+++ b/ber.go
@@ -2,6 +2,7 @@ package ber
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"reflect"
@@ -201,7 +202,7 @@ func ReadPacket(reader io.Reader) (*Packet, error) {
 	datalen := uint64(buf[1])
 
 	if Debug {
-		fmt.Printf("Read: datalen = %d len(buf) = %d ", datalen, len(buf))
+		fmt.Printf("Read: datalen = %d, len(buf) = %d, buf = ", datalen, len(buf))
 
 		for _, b := range buf {
 			fmt.Printf("%02X ", b)
@@ -225,7 +226,7 @@ func ReadPacket(reader io.Reader) (*Packet, error) {
 		datalen = DecodeInteger(buf[2 : 2+a])
 
 		if Debug {
-			fmt.Printf("Read: a = %d  idx = %d  datalen = %d  len(buf) = %d", a, idx, datalen, len(buf))
+			fmt.Printf("Read: a = %d, idx = %d, datalen = %d, len(buf) = %d, buf = ", a, idx, datalen, len(buf))
 
 			for _, b := range buf {
 				fmt.Printf("%02X ", b)
@@ -243,19 +244,23 @@ func ReadPacket(reader io.Reader) (*Packet, error) {
 	}
 
 	if Debug {
-		fmt.Printf("Read: len( buf ) = %d  idx=%d datalen=%d idx+datalen=%d\n", len(buf), idx, datalen, idx+datalen)
+		fmt.Printf("Read: len(buf) = %d, idx = %d, datalen = %d, idx+datalen = %d, buf = ", len(buf), idx, datalen, idx+datalen)
 
 		for _, b := range buf {
 			fmt.Printf("%02X ", b)
 		}
+
+		fmt.Printf("\n")
 	}
 
 	p := DecodePacket(buf)
-
+	if p == nil {
+		return nil, errors.New("Failed to decode a BER packet")
+	}
 	return p, nil
 }
 
-func DecodeString(data []byte) (string) {
+func DecodeString(data []byte) string {
 	return string(data)
 }
 
@@ -310,7 +315,9 @@ func decodePacket(data []byte) (*Packet, []byte) {
 	if Debug {
 		fmt.Printf("decodePacket: enter %d\n", len(data))
 	}
-
+	if len(data) < 2 {
+		return nil, data
+	}
 	p := new(Packet)
 
 	p.ClassType = data[0] & ClassBitmask
@@ -322,9 +329,15 @@ func decodePacket(data []byte) (*Packet, []byte) {
 
 	if datalen&128 != 0 {
 		datalen -= 128
+		if uint64(len(data)) < 2+datalen {
+			return nil, data
+		}
 		datapos += datalen
 		datalen = DecodeInteger(data[2 : 2+datalen])
 	}
+	if Debug {
+		fmt.Printf("decodePacket: datalen %d, datapos %d\n", datalen, datapos)
+	}
 
 	p.Data = new(bytes.Buffer)
 
@@ -332,6 +345,10 @@ func decodePacket(data []byte) (*Packet, []byte) {
 
 	p.Value = nil
 
+	if uint64(len(data)) < datapos+datalen {
+		return nil, data
+	}
+
 	value_data := data[datapos : datapos+datalen]
 
 	if p.TagType == TypeConstructed {
@@ -339,6 +356,9 @@ func decodePacket(data []byte) (*Packet, []byte) {
 			var child *Packet
 
 			child, value_data = decodePacket(value_data)
+			if child == nil {
+				return nil, data
+			}
 			p.AppendChild(child)
 		}
 	} else if p.ClassType == ClassUniversal {
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..1f6e72b
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/nmcclain/asn1-ber
+
+go 1.14