--- a/testing/taskcluster/taskcluster_graph/try_test_parser.py
+++ b/testing/taskcluster/taskcluster_graph/try_test_parser.py
@@ -12,16 +12,18 @@ def parse_test_opts(input_str):
     token = ''
     in_platforms = False
 
     def add_test(value):
         cur_test['test'] = value.strip()
         tests.insert(0, cur_test)
 
     def add_platform(value):
+        # Ensure platforms exists...
+        cur_test['platforms'] = cur_test.get('platforms', [])
         cur_test['platforms'].insert(0, value.strip())
 
     # This might be somewhat confusing but we parse the string _backwards_ so
     # there is no ambiguity over what state we are in.
     for char in reversed(input_str):
 
         # , indicates exiting a state
         if char == ',':
@@ -40,17 +42,16 @@ def parse_test_opts(input_str):
         elif char == '[':
             # Exiting platform state entering test state.
             add_platform(token)
             token = ''
             in_platforms = False
         elif char == ']':
             # Entering platform state.
             in_platforms = True
-            cur_test['platforms'] = []
         else:
             # Accumulator.
             token = char + token
 
     # Handle any left over tokens.
     if token:
         add_test(token)
 

--- a/testing/taskcluster/tests/test_try_test_parser.py
+++ b/testing/taskcluster/tests/test_try_test_parser.py
@@ -25,15 +25,27 @@ class TryTestParserTest(unittest.TestCas
                 { 'test': 'bar', 'platforms': ['b'] },
                 { 'test': 'baz' },
                 { 'test': 'qux', 'platforms': ['z'] },
                 { 'test': 'a' }
             ]
         )
 
         self.assertEquals(
+            parse_test_opts('mochitest-3[Ubuntu,10.6,10.8,Windows XP,Windows 7,Windows 8]'),
+            [
+                {
+                    'test': 'mochitest-3',
+                    'platforms': [
+                        'Ubuntu', '10.6', '10.8', 'Windows XP', 'Windows 7', 'Windows 8'
+                    ]
+                }
+            ]
+        )
+
+        self.assertEquals(
             parse_test_opts(''),
             []
         )
 
 if __name__ == '__main__':
     mozunit.main()