diff --git a/asn1.js b/asn1.js
index 0ce75e5..58a18e4 100644
--- a/asn1.js
+++ b/asn1.js
@@ -459,6 +459,14 @@ export class ASN1 {
             let d1 = this.stream.parseOctetString(content, content + len, maxLength);
             return '(' + d1.size + ' byte)\n' + d1.str;
         }
+        if (len === 0) {
+            switch (this.tag.tagNumber) {
+                case 1:
+                case 2:
+                case 6:
+	                return "invalid length 0";
+            }
+        }
         switch (this.tag.tagNumber) {
         case 0x01: // BOOLEAN
             return (this.stream.get(content) === 0) ? 'false' : 'true';
-- 
2.51.2


From 85ec3690f6394270c6c57a4b2d5d813ad265cbc1 Mon Sep 17 00:00:00 2001
From: Henri Manson <h.manson@aal-audio.com>
Date: Mon, 25 Aug 2025 10:28:47 +0000
Subject: [PATCH 2/3] add comments

---
 asn1.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/asn1.js b/asn1.js
index 58a18e4..f732b3b 100644
--- a/asn1.js
+++ b/asn1.js
@@ -461,9 +461,9 @@ export class ASN1 {
         }
         if (len === 0) {
             switch (this.tag.tagNumber) {
-                case 1:
-                case 2:
-                case 6:
+                case 0x01: // BOOLEAN
+                case 0x02: // INTEGER
+                case 0x06: // OBJECT_IDENTIFIER
 	                return "invalid length 0";
             }
         }
-- 
2.51.2


From 0bd079b7759e701ab0f0cf06c5125643d4be6f3c Mon Sep 17 00:00:00 2001
From: Lapo Luchini <lapo@lapo.it>
Date: Thu, 23 Oct 2025 20:51:08 +0000
Subject: [PATCH 3/3] Use existing switch.

---
 asn1.js | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/asn1.js b/asn1.js
index f732b3b..97a2eb3 100644
--- a/asn1.js
+++ b/asn1.js
@@ -459,24 +459,19 @@ export class ASN1 {
             let d1 = this.stream.parseOctetString(content, content + len, maxLength);
             return '(' + d1.size + ' byte)\n' + d1.str;
         }
-        if (len === 0) {
-            switch (this.tag.tagNumber) {
-                case 0x01: // BOOLEAN
-                case 0x02: // INTEGER
-                case 0x06: // OBJECT_IDENTIFIER
-	                return "invalid length 0";
-            }
-        }
         switch (this.tag.tagNumber) {
         case 0x01: // BOOLEAN
+            if (len === 0) return 'invalid length 0';
             return (this.stream.get(content) === 0) ? 'false' : 'true';
         case 0x02: // INTEGER
+            if (len === 0) return 'invalid length 0';
             return this.stream.parseInteger(content, content + len);
         case 0x03: { // BIT_STRING
             let d = recurse(this, 'parseBitString', maxLength);
             return '(' + d.size + ' bit)\n' + d.str;
         }
         case 0x04: { // OCTET_STRING
+            if (len === 0) return 'invalid length 0';
             let d = recurse(this, 'parseOctetString', maxLength);
             return '(' + d.size + ' byte)\n' + d.str;
         }