diff --git a/corpus/preprocessor.txt b/corpus/preprocessor.txt
index 4180bdf..542a7d0 100644
--- a/corpus/preprocessor.txt
+++ b/corpus/preprocessor.txt
@@ -133,3 +133,13 @@ int main() {
         (return_statement (number_literal))
         (preproc_else
           (return_statement (number_literal)))))))
+
+====================================
+Unknown preprocessor directives
+====================================
+
+#pragma mark - UIViewController
+
+---
+
+(translation_unit (preproc_call (preproc_directive) (preproc_arg)))
diff --git a/grammar.js b/grammar.js
index a077c38..321c499 100644
--- a/grammar.js
+++ b/grammar.js
@@ -149,7 +149,7 @@ module.exports = grammar({
       repeat($._compound_statement_item)
     ),
 
-    preproc_directive: $ => /#[ \t]+\a\w*/,
+    preproc_directive: $ => /#[ \t]*\a\w*/,
     preproc_arg: $ => token(prec(-1, repeat1(choice(/./, '\\\n')))),
 
     // Main Grammar