diff --git a/mdsplit.py b/mdsplit.py
index 19e2234..b64da0d 100755
--- a/mdsplit.py
+++ b/mdsplit.py
@@ -124,9 +124,12 @@ class Line:
     """
     Detect code blocks and ATX headings.
 
-    Headings according to commonmark:
+    Headings are detected according to commonmark, e.g.:
     - only 6 valid levels
     - up to three spaces before the first # is ok
+    - empty heading is valid
+    - closing hashes are stripped
+    - whitespace around title are stripped
     """
 
     def __init__(self, line):
@@ -134,10 +137,17 @@ def __init__(self, line):
         self.heading_level = 0
         self.heading_title = None
 
-        result = re.search("^[ ]?[ ]?[ ]?(#+) (.*)", line)
-        if result is not None and len(result[1]) <= MAX_HEADING_LEVEL:
+        result = re.search("^[ ]{0,3}(#+)(.*)", line)
+        if result is not None and (len(result[1]) <= MAX_HEADING_LEVEL):
+            title = result[2]
+            if len(title) > 0 and not (title.startswith(" ") or title.startswith("\t")):
+                # if there is a title it must start with space or tab
+                return
             self.heading_level = len(result[1])
-            self.heading_title = result[2]
+
+            # TODO strip whitespace and closing hashes
+            title = title.strip().rstrip("#").rstrip()
+            self.heading_title = title
 
     def is_fence(self):
         for fence in FENCES:
diff --git a/test_mdsplit.py b/test_mdsplit.py
index 6acee6a..3037d1b 100644
--- a/test_mdsplit.py
+++ b/test_mdsplit.py
@@ -42,6 +42,22 @@ def test_line():
     line = Line("    # four spaces are too much")
     assert not line.is_heading()
 
+    line = Line("#At least one space or tab required after heading")
+    assert not line.is_heading()
+
+    line = Line("#\ta tab is ok")
+    assert line.is_heading()
+
+    line = Line("###")  # headings without title (also without a space) are allowed
+    assert line.heading_level == 3
+    assert line.heading_title == ""
+
+    line = Line("#\t  please strip\t\t  ")
+    assert line.heading_title == "please strip"
+
+    line = Line("## strip rightmost hashes #########  ")
+    assert line.heading_title == "strip rightmost hashes"
+
 
 @pytest.mark.parametrize("max_level", [1, 3])
 def test_split_by_heading_simple(max_level):