diff --git a/src/llhttp/constants.ts b/src/llhttp/constants.ts
index 64e992ad..e1ba48a8 100644
--- a/src/llhttp/constants.ts
+++ b/src/llhttp/constants.ts
@@ -60,6 +60,7 @@ export enum LENIENT_FLAGS {
   CHUNKED_LENGTH = 1 << 1,
   KEEP_ALIVE = 1 << 2,
   TRANSFER_ENCODING = 1 << 3,
+  VERSION = 1 << 4,
 }
 
 export enum METHODS {
diff --git a/src/llhttp/http.ts b/src/llhttp/http.ts
index f46d8946..e44c8598 100644
--- a/src/llhttp/http.ts
+++ b/src/llhttp/http.ts
@@ -244,8 +244,27 @@ export class HTTP {
       .match('HTTP/', this.update('type', TYPE.RESPONSE, 'res_http_major'))
       .otherwise(p.error(ERROR.INVALID_CONSTANT, 'Invalid word encountered'));
 
-    // Response
+    const checkVersion = (destination: string): Node => {
+      return this.testLenientFlags(LENIENT_FLAGS.VERSION,
+        {
+          1: n(destination),
+        },
+        this.load('http_major', {
+          0: this.load('http_minor', {
+            9: n(destination),
+          }, p.error(ERROR.INVALID_VERSION, 'Invalid HTTP version')),
+          1: this.load('http_minor', {
+            0: n(destination),
+            1: n(destination),
+          }, p.error(ERROR.INVALID_VERSION, 'Invalid HTTP version')),
+          2: this.load('http_minor', {
+            0: n(destination),
+          }, p.error(ERROR.INVALID_VERSION, 'Invalid HTTP version')),
+        }, p.error(ERROR.INVALID_VERSION, 'Invalid HTTP version')),
+      );
+    };
 
+    // Response
     n('start_res')
       .match('HTTP/', n('res_http_major'))
       .otherwise(p.error(ERROR.INVALID_CONSTANT, 'Expected HTTP/'));
@@ -259,7 +278,7 @@ export class HTTP {
       .otherwise(p.error(ERROR.INVALID_VERSION, 'Expected dot'));
 
     n('res_http_minor')
-      .select(MINOR, this.store('http_minor', 'res_http_end'))
+      .select(MINOR, this.store('http_minor', checkVersion('res_http_end')))
       .otherwise(p.error(ERROR.INVALID_VERSION, 'Invalid minor version'));
 
     n('res_http_end')
@@ -365,7 +384,7 @@ export class HTTP {
       .otherwise(p.error(ERROR.INVALID_VERSION, 'Expected dot'));
 
     n('req_http_minor')
-      .select(MINOR, this.store('http_minor', 'req_http_end'))
+      .select(MINOR, this.store('http_minor', checkVersion('req_http_end')))
       .otherwise(p.error(ERROR.INVALID_VERSION, 'Invalid minor version'));
 
     n('req_http_end').otherwise(this.load('method', {
diff --git a/test/fixtures/extra.c b/test/fixtures/extra.c
index 93d74735..64e9ae97 100644
--- a/test/fixtures/extra.c
+++ b/test/fixtures/extra.c
@@ -88,11 +88,22 @@ void llhttp__test_init_request_lenient_transfer_encoding(llparse_t* s) {
 }
 
 
+void llhttp__test_init_request_lenient_version(llparse_t* s) {
+  llhttp__test_init_request(s);
+  s->lenient_flags |= LENIENT_VERSION;
+}
+
+
 void llhttp__test_init_response_lenient_keep_alive(llparse_t* s) {
   llhttp__test_init_response(s);
   s->lenient_flags |= LENIENT_KEEP_ALIVE;
 }
 
+void llhttp__test_init_response_lenient_version(llparse_t* s) {
+  llhttp__test_init_response(s);
+  s->lenient_flags |= LENIENT_VERSION;
+}
+
 
 void llhttp__test_finish(llparse_t* s) {
   llparse__print(NULL, NULL, "finish=%d", s->finish);
diff --git a/test/fixtures/index.ts b/test/fixtures/index.ts
index a9450da8..9ac0fd05 100644
--- a/test/fixtures/index.ts
+++ b/test/fixtures/index.ts
@@ -11,6 +11,7 @@ import * as llhttp from '../../src/llhttp';
 export type TestType = 'request' | 'response' | 'request-lenient-headers' |
   'request-lenient-chunked-length' | 'request-lenient-transfer-encoding' |
   'request-lenient-keep-alive' | 'response-lenient-keep-alive' |
+  'request-lenient-version' | 'response-lenient-version' |
   'request-finish' | 'response-finish' |
   'none' | 'url';
 
@@ -66,7 +67,9 @@ export async function build(
       ty === 'request-lenient-chunked-length' ||
       ty === 'request-lenient-transfer-encoding' ||
       ty === 'request-lenient-keep-alive' ||
-      ty === 'response-lenient-keep-alive') {
+      ty === 'response-lenient-keep-alive' ||
+      ty === 'request-lenient-version' ||
+      ty === 'response-lenient-version') {
     extra.push(
       `-DLLPARSE__TEST_INIT=llhttp__test_init_${ty.replace(/-/g, '_')}`);
   } else if (ty === 'request-finish' || ty === 'response-finish') {
diff --git a/test/md-test.ts b/test/md-test.ts
index 4947ab14..20d9b3d2 100644
--- a/test/md-test.ts
+++ b/test/md-test.ts
@@ -79,34 +79,30 @@ const http: IFixtureMap = {
     'none': buildMode('loose', 'none'),
     'request': buildMode('loose', 'request'),
     'request-finish': buildMode('loose', 'request-finish'),
-    'request-lenient-chunked-length':
-      buildMode('loose', 'request-lenient-chunked-length'),
+    'request-lenient-chunked-length': buildMode('loose', 'request-lenient-chunked-length'),
     'request-lenient-headers': buildMode('loose', 'request-lenient-headers'),
-    'request-lenient-keep-alive': buildMode(
-      'loose', 'request-lenient-keep-alive'),
-    'request-lenient-transfer-encoding':
-      buildMode('loose', 'request-lenient-transfer-encoding'),
+    'request-lenient-keep-alive': buildMode( 'loose', 'request-lenient-keep-alive'),
+    'request-lenient-transfer-encoding': buildMode('loose', 'request-lenient-transfer-encoding'),
+    'request-lenient-version': buildMode( 'loose', 'request-lenient-version'),
     'response': buildMode('loose', 'response'),
     'response-finish': buildMode('loose', 'response-finish'),
-    'response-lenient-keep-alive': buildMode(
-      'loose', 'response-lenient-keep-alive'),
+    'response-lenient-keep-alive': buildMode( 'loose', 'response-lenient-keep-alive'),
+    'response-lenient-version': buildMode( 'loose', 'response-lenient-version'),
     'url': buildMode('loose', 'url'),
   },
   strict: {
     'none': buildMode('strict', 'none'),
     'request': buildMode('strict', 'request'),
     'request-finish': buildMode('strict', 'request-finish'),
-    'request-lenient-chunked-length':
-      buildMode('strict', 'request-lenient-chunked-length'),
+    'request-lenient-chunked-length': buildMode('strict', 'request-lenient-chunked-length'),
     'request-lenient-headers': buildMode('strict', 'request-lenient-headers'),
-    'request-lenient-keep-alive': buildMode(
-      'strict', 'request-lenient-keep-alive'),
-    'request-lenient-transfer-encoding':
-      buildMode('strict', 'request-lenient-transfer-encoding'),
+    'request-lenient-keep-alive': buildMode( 'strict', 'request-lenient-keep-alive'),
+    'request-lenient-transfer-encoding': buildMode('strict', 'request-lenient-transfer-encoding'),
+    'request-lenient-version': buildMode( 'strict', 'request-lenient-version'),
     'response': buildMode('strict', 'response'),
     'response-finish': buildMode('strict', 'response-finish'),
-    'response-lenient-keep-alive': buildMode(
-      'strict', 'response-lenient-keep-alive'),
+    'response-lenient-keep-alive': buildMode('strict', 'response-lenient-keep-alive'),
+    'response-lenient-version': buildMode( 'strict', 'response-lenient-version'),
     'url': buildMode('strict', 'url'),
   },
 };
@@ -171,8 +167,12 @@ function run(name: string): void {
           types = [ 'request-lenient-keep-alive' ];
         } else if (meta.type === 'request-lenient-transfer-encoding') {
           types = [ 'request-lenient-transfer-encoding' ];
+        } else if (meta.type === 'request-lenient-version') {
+          types = [ 'request-lenient-version' ];
         } else if (meta.type === 'response-lenient-keep-alive') {
           types = [ 'response-lenient-keep-alive' ];
+        } else if (meta.type === 'response-lenient-version') {
+          types = [ 'response-lenient-version' ];
         } else if (meta.type === 'response-only') {
           types = [ 'response' ];
         } else if (meta.type === 'request-finish') {
@@ -278,6 +278,7 @@ function run(name: string): void {
 
 run('request/sample');
 run('request/lenient-headers');
+run('request/lenient-version');
 run('request/method');
 run('request/uri');
 run('request/connection');
@@ -292,5 +293,5 @@ run('response/content-length');
 run('response/transfer-encoding');
 run('response/invalid');
 run('response/finish');
-
+run('request/lenient-version');
 run('url');
diff --git a/test/request/invalid.md b/test/request/invalid.md
index c2b6b4ed..2154ddf3 100644
--- a/test/request/invalid.md
+++ b/test/request/invalid.md
@@ -229,4 +229,18 @@ off=33 len=5 span[header_field]="Dummy"
 off=39 header_field complete
 off=40 len=1 span[header_value]="x"
 off=42 error code=25 reason="Missing expected CR after header value"
+```
+
+### Invalid HTTP version
+
+<!-- meta={"type": "request", "noScan": true} -->
+```http
+GET / HTTP/5.6
+```
+
+```log
+off=0 message begin
+off=4 len=1 span[url]="/"
+off=6 url complete
+off=14 error code=9 reason="Invalid HTTP version"
 ```
\ No newline at end of file
diff --git a/test/request/lenient-version.md b/test/request/lenient-version.md
new file mode 100644
index 00000000..7fae4e2b
--- /dev/null
+++ b/test/request/lenient-version.md
@@ -0,0 +1,19 @@
+Lenient HTTP version parsing
+============================
+
+### Invalid HTTP version with lenient
+
+<!-- meta={"type": "request-lenient-version"} -->
+```http
+GET / HTTP/5.6
+
+
+```
+
+```log
+off=0 message begin
+off=4 len=1 span[url]="/"
+off=6 url complete
+off=18 headers complete method=1 v=5/6 flags=0 content_length=0
+off=18 message complete
+```
\ No newline at end of file
diff --git a/test/response/invalid.md b/test/response/invalid.md
index 60bd3042..bbdc40ba 100644
--- a/test/response/invalid.md
+++ b/test/response/invalid.md
@@ -106,3 +106,17 @@ off=21 header_field complete
 off=22 len=1 span[header_value]="1"
 off=24 error code=3 reason="Missing expected LF after header value"
 ```
+
+### Invalid HTTP version
+
+<!-- meta={"type": "response"} -->
+```http
+HTTP/5.6 200 OK
+
+
+```
+
+```log
+off=0 message begin
+off=8 error code=9 reason="Invalid HTTP version"
+```
\ No newline at end of file
diff --git a/test/response/lenient-version.md b/test/response/lenient-version.md
new file mode 100644
index 00000000..94642b38
--- /dev/null
+++ b/test/response/lenient-version.md
@@ -0,0 +1,18 @@
+Lenient HTTP version parsing
+============================
+
+### Invalid HTTP version with lenient
+
+<!-- meta={"type": "response-lenient-version"} -->
+```http
+HTTP/5.6 200 OK
+
+
+```
+
+```log
+off=0 message begin
+off=13 len=2 span[status]="OK"
+off=17 status complete
+off=19 headers complete status=200 v=5/6 flags=0 content_length=0
+```