diff --git a/mode/latex.py b/mode/latex.py
index 3aa756f..bdd44e7 100644
--- a/mode/latex.py
+++ b/mode/latex.py
@@ -9,15 +9,16 @@ class ArgumentGrammar(Grammar): rules = [PatternRule(r'data', r'[^}]+')]
 class StringGrammar1(Grammar): rules = [PatternRule(r'data', r"[^']+")]
 class StringGrammar2(Grammar): rules = [PatternRule(r'data', r"(?:[^']|'(?!'))+")]
 
-class FalseGrammar(Grammar): rules = [
-    PatternRule('data', r'[^\\]+'),
-    RegionRule('comment', r'\\if', None, r'\\fi'),
-]
+class FalseGrammar(Grammar):
+    rules = [
+        PatternRule('data', r'[^\\]+'),
+        RegionRule('comment', r'\\if', None, r'\\fi'),
+    ]
 
 class LatexGrammar(Grammar):
     rules = [
         PatternRule(r'comment', r'\%.*$'),
-        RegionRule('comment', r'\\iffalse', Grammar, r'\\fi'),
+        RegionRule('comment', r'\\iffalse', FalseGrammar, r'\\fi'),
         PatternRule(r'latex_wrapper', r'\\(?:begin|end)'),
         PatternRule(r'latex_control', r'\\[a-zA-Z]+'),
         RegionRule(r'latex_argument', r'{', ArgumentGrammar, r'}'),