diff --git a/grammars/scss.cson b/grammars/scss.cson
index c9ea0ff..194126b 100644
--- a/grammars/scss.cson
+++ b/grammars/scss.cson
@@ -396,16 +396,16 @@
   'at_rule_mixin':
     'patterns': [
       {
-        'begin': '\\s*((@)mixin) ([\\w-]*)\\s*\\('
-        'captures':
+        'begin': '(?<=@mixin)\\s+([\\w-]+)\\s*(\\()'
+        'beginCaptures':
           '1':
-            'name': 'keyword.control.at-rule.mixin.scss'
-          '2':
-            'name': 'punctuation.definition.keyword.scss'
-          '3':
             'name': 'entity.name.function.scss'
-        'comment': 'Mixin with Attributes'
+          '2':
+            'name': 'punctuation.definition.parameters.begin.bracket.round.scss'
         'end': '\\)'
+        'endCaptures':
+          '0':
+            'name': 'punctuation.definition.parameters.end.bracket.round.scss'
         'name': 'meta.at-rule.mixin.scss'
         'patterns': [
           {
@@ -414,31 +414,29 @@
         ]
       }
       {
+        'match': '(?<=@mixin)\\s+([\\w-]+)'
+        'captures':
+          '1':
+            'name': 'entity.name.function.scss'
+        'name': 'meta.at-rule.mixin.scss'
+      }
+      {
+        'match': '((@)mixin)\\b'
         'captures':
           '1':
             'name': 'keyword.control.at-rule.mixin.scss'
           '2':
             'name': 'punctuation.definition.keyword.scss'
-          '3':
-            'name': 'entity.name.function.scss'
-        'comment': 'Simple Mixin'
-        'match': '^\\s*((@)mixin) ([\\w-]{1,})'
         'name': 'meta.at-rule.mixin.scss'
       }
     ]
   'at_rule_namespace':
     'patterns': [
       {
-        'begin': '\\s*((@)namespace)\\s+(?=url)'
-        'captures':
-          '1':
-            'name': 'keyword.control.at-rule.namespace.scss'
-          '2':
-            'name': 'punctuation.definition.keyword.scss'
-          '3':
-            'name': 'support.function.misc.scss'
-        'comment': 'Namespace without prefix'
-        'end': '\\s*((?=;|$))'
+        # Define the default namespace with url()
+        # MUST be on the top
+        'begin': '(?<=@namespace)\\s+(?=url)'
+        'end': '(?=;|$)'
         'name': 'meta.at-rule.namespace.scss'
         'patterns': [
           {
@@ -453,16 +451,13 @@
         ]
       }
       {
-        'begin': '\\s*((@)namespace) ([\\w-]*)\\s*'
+        # Define the default namespace with string, or
+        # a namespace prefix with string or url()
+        'begin': '(?<=@namespace)\\s+([\\w-]*)'
         'captures':
           '1':
-            'name': 'keyword.control.at-rule.namespace.scss'
-          '2':
-            'name': 'punctuation.definition.keyword.scss'
-          '3':
-            'name': 'entity.name.function.scss'
-        'comment': 'Namespace'
-        'end': '\\s*((?=;|$))'
+            'name': 'entity.name.namespace-prefix.scss'
+        'end': '(?=;|$)'
         'name': 'meta.at-rule.namespace.scss'
         'patterns': [
           {
@@ -479,6 +474,15 @@
           }
         ]
       }
+      {
+        'match': '((@)namespace)\\b'
+        'captures':
+          '1':
+            'name': 'keyword.control.at-rule.namespace.scss'
+          '2':
+            'name': 'punctuation.definition.keyword.scss'
+        'name': 'meta.at-rule.namespace.scss'
+      }
     ]
   'at_rule_option':
     'captures':
diff --git a/spec/scss-spec.coffee b/spec/scss-spec.coffee
index a8f33a5..66bb9a2 100644
--- a/spec/scss-spec.coffee
+++ b/spec/scss-spec.coffee
@@ -40,6 +40,51 @@ describe 'SCSS grammar', ->
       expect(tokens[0]).toEqual value: '@', scopes: ['source.css.scss', 'meta.at-rule.at-root.scss', 'keyword.control.at-rule.at-root.scss', 'punctuation.definition.keyword.scss']
       expect(tokens[1]).toEqual value: 'at-root', scopes: ['source.css.scss', 'meta.at-rule.at-root.scss', 'keyword.control.at-rule.at-root.scss']
 
+  describe '@mixin', ->
+    it 'tokenizes solitary @mixin correctly', ->
+      {tokens} = grammar.tokenizeLine '@mixin'
+
+      expect(tokens[0]).toEqual value: '@', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'keyword.control.at-rule.mixin.scss', 'punctuation.definition.keyword.scss']
+      expect(tokens[1]).toEqual value: 'mixin', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'keyword.control.at-rule.mixin.scss']
+
+    it 'tokenizes @mixin with no arguments correctly', ->
+      {tokens} = grammar.tokenizeLine '@mixin media{}'
+
+      expect(tokens[0]).toEqual value: '@', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'keyword.control.at-rule.mixin.scss', 'punctuation.definition.keyword.scss']
+      expect(tokens[1]).toEqual value: 'mixin', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'keyword.control.at-rule.mixin.scss']
+      expect(tokens[3]).toEqual value: 'media', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'entity.name.function.scss']
+      expect(tokens[4]).toEqual value: '{', scopes: ['source.css.scss', 'meta.property-list.scss', 'punctuation.section.property-list.begin.bracket.curly.scss']
+
+    it 'tokenizes @mixin with arguments correctly', ->
+      {tokens} = grammar.tokenizeLine '@mixin media ($width){}'
+
+      expect(tokens[3]).toEqual value: 'media', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'entity.name.function.scss']
+      expect(tokens[5]).toEqual value: '(', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'punctuation.definition.parameters.begin.bracket.round.scss']
+      expect(tokens[7]).toEqual value: ')', scopes: ['source.css.scss', 'meta.at-rule.mixin.scss', 'punctuation.definition.parameters.end.bracket.round.scss']
+      expect(tokens[8]).toEqual value: '{', scopes: ['source.css.scss', 'meta.property-list.scss', 'punctuation.section.property-list.begin.bracket.curly.scss']
+
+  describe '@namespace', ->
+    it 'tokenizes solitary @namespace correctly', ->
+      {tokens} = grammar.tokenizeLine '@namespace'
+
+      expect(tokens[0]).toEqual value: '@', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'keyword.control.at-rule.namespace.scss', 'punctuation.definition.keyword.scss']
+      expect(tokens[1]).toEqual value: 'namespace', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'keyword.control.at-rule.namespace.scss']
+
+    it 'tokenizes default namespace definition with url() correctly', ->
+      {tokens} = grammar.tokenizeLine '@namespace url(XML-namespace-URL);'
+
+      expect(tokens[0]).toEqual value: '@', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'keyword.control.at-rule.namespace.scss', 'punctuation.definition.keyword.scss']
+      expect(tokens[1]).toEqual value: 'namespace', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'keyword.control.at-rule.namespace.scss']
+      expect(tokens[3]).toEqual value: 'url', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'support.function.misc.scss']
+
+    it 'tokenizes namespace prefix definition with url() correctly', ->
+      {tokens} = grammar.tokenizeLine '@namespace prefix url(XML-namespace-URL);'
+
+      expect(tokens[0]).toEqual value: '@', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'keyword.control.at-rule.namespace.scss', 'punctuation.definition.keyword.scss']
+      expect(tokens[1]).toEqual value: 'namespace', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'keyword.control.at-rule.namespace.scss']
+      expect(tokens[3]).toEqual value: 'prefix', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'entity.name.namespace-prefix.scss']
+      expect(tokens[5]).toEqual value: 'url', scopes: ['source.css.scss', 'meta.at-rule.namespace.scss', 'support.function.misc.scss']
+
   describe '@page', ->
     it 'tokenizes it correctly', ->
       tokens = grammar.tokenizeLines """