diff --git a/lib/index.js b/lib/index.js
index fd0aa71..6ae94a4 100755
--- a/lib/index.js
+++ b/lib/index.js
@@ -15,8 +15,8 @@ const internals = {};
     parameter  = token "=" ( token / quoted-string )
 */
 
-//                             1: type/subtype    2: params
-internals.contentTypeRegex = /^([^\/\s]+\/[^\s;]+)([ \t;][^\r\n]*)?$/;
+//                             1: type/subtype                                           2: params
+internals.contentTypeRegex = /^([A-Za-z0-9!#$%&'*+.^_`|~-]+\/[A-Za-z0-9!#$%&'*+.^_`|~-]+)([ \t;][^\r\n]*)?$/;
 
 //                                             1: "b"   2: b
 internals.charsetParamRegex = /;\s*charset=(?:"([^"]+)"|([^;"\s]+))/i;
@@ -45,6 +45,10 @@ exports.type = function (header) {
         const param = params.match(internals.charsetParamRegex);
         if (param) {
             result.charset = (param[1] || param[2]).toLowerCase();
+
+            if (internals.charsetParamRegex.test(params.slice(param.index + param[0].length))) {
+                throw Boom.badRequest('Invalid content-type header: duplicate parameter');
+            }
         }
     }
 
@@ -53,6 +57,10 @@ exports.type = function (header) {
             const param = params.match(internals.boundaryParamRegex);
             if (param) {
                 result.boundary = param[1] || param[2];
+
+                if (internals.boundaryParamRegex.test(params.slice(param.index + param[0].length))) {
+                    throw Boom.badRequest('Invalid content-type header: duplicate parameter');
+                }
             }
         }
 
@@ -104,12 +112,30 @@ exports.disposition = function (header) {
     }
 
     const result = {};
+    const extKeys = new Set();
     parameters.replace(internals.contentDispositionParamRegex, ($0, $1, $2, $3, $4, $5) => {
 
         if ($1 === '__proto__') {
             throw Boom.badRequest('Invalid content-disposition header format includes invalid parameters');
         }
 
+        if (result[$1] !== undefined) {
+            if ($2 && !extKeys.has($1)) {
+                // ext-value overriding regular value - allowed per RFC 6266 Section 4.3
+            }
+            else if (!$2 && extKeys.has($1)) {
+                // Regular value after ext-value - ignore (keep ext-value)
+                return;
+            }
+            else {
+                throw Boom.badRequest('Invalid content-disposition header format includes invalid parameters');
+            }
+        }
+
+        if ($2) {
+            extKeys.add($1);
+        }
+
         let value;
 
         if ($2) {
@@ -118,7 +144,7 @@ exports.disposition = function (header) {
             }
 
             try {
-                value = decodeURIComponent($3.split('\'')[2]);
+                value = decodeURIComponent($3.slice($3.indexOf('\'', $3.indexOf('\'') + 1) + 1));
             }
             catch (err) {
                 throw Boom.badRequest('Invalid content-disposition header format includes invalid parameters');
diff --git a/test/index.js b/test/index.js
index c386c26..679b6eb 100755
--- a/test/index.js
+++ b/test/index.js
@@ -117,7 +117,7 @@ describe('type()', () => {
 
         const header = `multipart/form-data ${new Array(80000).join(';boundary=#')}`;
         const now = Date.now();
-        Content.type(header);
+        expect(() => Content.type(header)).to.throw('Invalid content-type header: duplicate parameter');
         expect(Date.now() - now).to.be.below(100);
     });
 
@@ -125,7 +125,7 @@ describe('type()', () => {
 
         const header = `text/plain ${new Array(80000).join(';charset=utf-8')}`;
         const now = Date.now();
-        Content.type(header);
+        expect(() => Content.type(header)).to.throw('Invalid content-type header: duplicate parameter');
         expect(Date.now() - now).to.be.below(100);
     });
 
@@ -141,6 +141,26 @@ describe('type()', () => {
 
         expect(() => Content.type('application/json\n; charset=utf-8')).to.throw('Invalid content-type header');
     });
+
+    it('errors on duplicate charset parameter', () => {
+
+        expect(() => Content.type('text/plain; charset=utf-8; charset=ascii')).to.throw('Invalid content-type header: duplicate parameter');
+    });
+
+    it('errors on duplicate boundary parameter', () => {
+
+        expect(() => Content.type('multipart/form-data; boundary=abc; boundary=def')).to.throw('Invalid content-type header: duplicate parameter');
+    });
+
+    it('errors on invalid token characters in type', () => {
+
+        expect(() => Content.type('text/html\x00')).to.throw('Invalid content-type header');
+    });
+
+    it('errors on invalid token characters in subtype', () => {
+
+        expect(() => Content.type('text/<html>')).to.throw('Invalid content-type header');
+    });
 });
 
 describe('disposition()', () => {
@@ -351,4 +371,58 @@ describe('disposition()', () => {
         const header = 'form-data; name="file"; filename="test.jpg"  ';
         expect(Content.disposition(header)).to.equal({ name: 'file', filename: 'test.jpg' });
     });
+
+    it('errors on constructor param', () => {
+
+        const header = 'form-data; name="file"; constructor=test';
+        expect(() => Content.disposition(header)).to.throw('Invalid content-disposition header format includes invalid parameters');
+    });
+
+    it('errors on toString param', () => {
+
+        const header = 'form-data; name="file"; toString=test';
+        expect(() => Content.disposition(header)).to.throw('Invalid content-disposition header format includes invalid parameters');
+    });
+
+    it('handles single quote in ext-value', () => {
+
+        const header = 'form-data; name="file"; filename*=utf-8\'en\'it\'s%20here.php';
+        expect(Content.disposition(header)).to.equal({ name: 'file', filename: 'it\'s here.php' });
+    });
+
+    it('errors on duplicate parameter names', () => {
+
+        const header = 'form-data; name="file"; filename="safe.txt"; filename="shell.php"';
+        expect(() => Content.disposition(header)).to.throw('Invalid content-disposition header format includes invalid parameters');
+    });
+
+    it('allows ext-value to override filename parameter', () => {
+
+        const header = 'form-data; name="file"; filename="fallback.jpg"; filename*=utf-8\'\'extended.jpg';
+        expect(Content.disposition(header)).to.equal({ name: 'file', filename: 'extended.jpg' });
+    });
+
+    it('keeps ext-value when filename parameter follows', () => {
+
+        const header = 'form-data; name="file"; filename*=utf-8\'\'extended.jpg; filename="fallback.jpg"';
+        expect(Content.disposition(header)).to.equal({ name: 'file', filename: 'extended.jpg' });
+    });
+
+    it('errors on duplicate ext-value parameters', () => {
+
+        const header = 'form-data; name="file"; filename*=utf-8\'\'a.jpg; filename*=utf-8\'\'b.jpg';
+        expect(() => Content.disposition(header)).to.throw('Invalid content-disposition header format includes invalid parameters');
+    });
+
+    it('errors on duplicate even when ext-value override is present', () => {
+
+        const header = 'form-data; name="avatar"; name*=utf-8\'\'admin; filename="safe.txt"; filename="shell.php"';
+        expect(() => Content.disposition(header)).to.throw('Invalid content-disposition header format includes invalid parameters');
+    });
+
+    it('errors on duplicate name parameters', () => {
+
+        const header = 'form-data; name="avatar"; name="admin"';
+        expect(() => Content.disposition(header)).to.throw('Invalid content-disposition header format includes invalid parameters');
+    });
 });