diff --git a/syntax.json b/syntax.json
index 808f963..978c116 100644
--- a/syntax.json
+++ b/syntax.json
@@ -429,6 +429,18 @@
       }
     ]
   },
+  {
+    "language": "RMarkdown",
+    "markers": [
+      {
+        "type": "block",
+        "pattern": {
+          "start": "<!--",
+          "end": "-->"
+        }
+      }
+    ]
+  },
   {
     "language": "Shell",
     "markers": [
@@ -721,4 +733,4 @@
       }
     ]
   }
-]
\ No newline at end of file
+]
diff --git a/tests/test_closed.diff b/tests/test_closed.diff
index 19df3f3..d3ee0fb 100644
--- a/tests/test_closed.diff
+++ b/tests/test_closed.diff
@@ -265,6 +265,18 @@ hello_world <- function() {
 -    #  This function should probably do something more interesting
 -    #  labels: help wanted
 }
+diff --git a/tests/example_file.rmd b/src/tests/example_file.rmd
+index 525e25d..ba4e68d 100644
+--- a/src/tests/example_file.rmd
++++ b/src/tests/example_file.rmd
+@@ -0,1 +0,0 @@
+- <!-- TODO: Check RMarkdown comments work -->
+diff --git a/tests/example_file.qmd b/src/tests/example_file.qmd
+index 525e25d..ba4e68d 100644
+--- a/src/tests/example_file.qmd
++++ b/src/tests/example_file.qmd
+@@ -0,1 +0,0 @@
+- <!-- TODO: Check RMarkdown comments work -->
 diff --git a/src/Swarm/Game/example.hs b/src/Swarm/Game/example.hs
 index 525e25d..ba4e68d 100644
 --- a/src/Swarm/Game/example.hs
diff --git a/tests/test_new.diff b/tests/test_new.diff
index 74c6e4a..4dd93f9 100644
--- a/tests/test_new.diff
+++ b/tests/test_new.diff
@@ -306,6 +306,20 @@ index 0000000..525e25d
 +    #  This function should probably do something more interesting
 +    #  labels: help wanted
 +}
+diff --git a/tests/example_file.rmd b/src/tests/example_file.rmd
+new file mode 100644
+index 0000000..525e25d
+--- /dev/null
++++ b/src/tests/example_file.rmd
+@@ -0,0 +0,1 @@
++<!-- TODO: Check RMarkdown comments work -->
+diff --git a/tests/example_file.qmd b/src/tests/example_file.qmd
+new file mode 100644
+index 0000000..525e25d
+--- /dev/null
++++ b/src/tests/example_file.qmd
+@@ -0,0 +0,1 @@
++<!-- TODO: Check RMarkdown comments work -->
 diff --git a/tests/config.jsonc b/tests/config.jsonc
 new file mode 100644
 index 0000000..525e25d
@@ -388,4 +402,4 @@ index 0000000..a6c6cb0
 +<!-- TODO: Add xaml support -->
 +<Label Text="why"/>
 +<!-- TODO: please -->
-+<Label Text="ok"/>
\ No newline at end of file
++<Label Text="ok"/>
diff --git a/tests/test_todo_parser.py b/tests/test_todo_parser.py
index c53f2d1..0b0c1f8 100644
--- a/tests/test_todo_parser.py
+++ b/tests/test_todo_parser.py
@@ -76,7 +76,7 @@ class NewIssueTests(unittest.TestCase):
         self.assertEqual(count_issues_for_file_type(self.raw_issues, 'twig'), 2)
 
     def test_md_issues(self):
-        self.assertEqual(count_issues_for_file_type(self.raw_issues, 'markdown'), 6)
+        self.assertEqual(count_issues_for_file_type(self.raw_issues, 'markdown'), 8)
 
     def test_r_issues(self):
         self.assertEqual(count_issues_for_file_type(self.raw_issues, 'r'), 2)
@@ -156,7 +156,7 @@ class ClosedIssueTests(unittest.TestCase):
         self.assertEqual(count_issues_for_file_type(self.raw_issues, 'twig'), 2)
 
     def test_md_issues(self):
-        self.assertEqual(count_issues_for_file_type(self.raw_issues, 'markdown'), 6)
+        self.assertEqual(count_issues_for_file_type(self.raw_issues, 'markdown'), 8)
 
     def test_r_issues(self):
         self.assertEqual(count_issues_for_file_type(self.raw_issues, 'r'), 2)