diff --git a/lark/load_grammar.py b/lark/load_grammar.py
index 8b2eaa8..cd36e4b 100644
--- a/lark/load_grammar.py
+++ b/lark/load_grammar.py
@@ -789,19 +789,19 @@ def _find_used_symbols(tree):
               for t in x.scan_values(lambda t: t.type in ('RULE', 'TERMINAL'))}
 
 class GrammarLoader:
-    ERRORS = {
-        'Unclosed parenthesis': ['a: (\n'],
-        'Umatched closing parenthesis': ['a: )\n', 'a: [)\n', 'a: (]\n'],
-        'Expecting rule or terminal definition (missing colon)': ['a\n', 'A\n', 'a->\n', 'A->\n', 'a A\n'],
-        'Illegal name for rules or terminals': ['Aa:\n'],
-        'Alias expects lowercase name': ['a: -> "a"\n'],
-        'Unexpected colon': ['a::\n', 'a: b:\n', 'a: B:\n', 'a: "a":\n'],
-        'Misplaced operator': ['a: b??', 'a: b(?)', 'a:+\n', 'a:?\n', 'a:*\n', 'a:|*\n'],
-        'Expecting option ("|") or a new rule or terminal definition': ['a:a\n()\n'],
-        'Terminal names cannot contain dots': ['A.B\n'],
-        '%import expects a name': ['%import "a"\n'],
-        '%ignore expects a value': ['%ignore %import\n'],
-    }
+    ERRORS = [
+        ('Unclosed parenthesis', ['a: (\n']),
+        ('Umatched closing parenthesis', ['a: )\n', 'a: [)\n', 'a: (]\n']),
+        ('Expecting rule or terminal definition (missing colon)', ['a\n', 'A\n', 'a->\n', 'A->\n', 'a A\n']),
+        ('Illegal name for rules or terminals', ['Aa:\n']),
+        ('Alias expects lowercase name', ['a: -> "a"\n']),
+        ('Unexpected colon', ['a::\n', 'a: b:\n', 'a: B:\n', 'a: "a":\n']),
+        ('Misplaced operator', ['a: b??', 'a: b(?)', 'a:+\n', 'a:?\n', 'a:*\n', 'a:|*\n']),
+        ('Expecting option ("|") or a new rule or terminal definition', ['a:a\n()\n']),
+        ('Terminal names cannot contain dots', ['A.B\n']),
+        ('%import expects a name', ['%import "a"\n']),
+        ('%ignore expects a value', ['%ignore %import\n']),
+    ]
 
     def __init__(self, re_module):
         terminals = [TerminalDef(name, PatternRE(value)) for name, value in TERMINALS.items()]
diff --git a/tests/test_grammar.py b/tests/test_grammar.py
index 88c8e22..363f897 100644
--- a/tests/test_grammar.py
+++ b/tests/test_grammar.py
@@ -12,7 +12,7 @@ class TestGrammar(TestCase):
         pass
 
     def test_errors(self):
-        for msg, examples in GrammarLoader.ERRORS.items():
+        for msg, examples in GrammarLoader.ERRORS:
             for example in examples:
                 try:
                     p = Lark(example)