diff --git a/org/keyword.go b/org/keyword.go
index d4bd233..c166b95 100644
--- a/org/keyword.go
+++ b/org/keyword.go
@@ -35,7 +35,7 @@ type Include struct {
 }
 
 var keywordRegexp = regexp.MustCompile(`^(\s*)#\+([^:]+):(\s+(.*)|$)`)
-var commentRegexp = regexp.MustCompile(`^(\s*)#(.*)`)
+var commentRegexp = regexp.MustCompile(`^(\s*)#\s(.*)`)
 
 var includeFileRegexp = regexp.MustCompile(`(?i)^"([^"]+)" (src|example|export) (\w+)$`)
 var attributeRegexp = regexp.MustCompile(`(?:^|\s+)(:[-\w]+)\s+(.*)$`)
diff --git a/org/org_writer.go b/org/org_writer.go
index 4b4d2a4..c502c76 100644
--- a/org/org_writer.go
+++ b/org/org_writer.go
@@ -207,7 +207,7 @@ func (w *OrgWriter) WriteNodeWithName(n NodeWithName) {
 }
 
 func (w *OrgWriter) WriteComment(c Comment) {
-	w.WriteString(w.indent + "#" + c.Content + "\n")
+	w.WriteString(w.indent + "# " + c.Content + "\n")
 }
 
 func (w *OrgWriter) WriteList(l List) { WriteNodes(w, l.Items...) }
diff --git a/org/testdata/keywords.html b/org/testdata/keywords.html
index 7e39d4b..06c3e27 100644
--- a/org/testdata/keywords.html
+++ b/org/testdata/keywords.html
@@ -25,3 +25,4 @@ named block
 </pre>
 </div>
 </div>
+<p>#not a comment because there&#39;s no space after the hashtag</p>
diff --git a/org/testdata/keywords.org b/org/testdata/keywords.org
index 440949d..dc59ed1 100644
--- a/org/testdata/keywords.org
+++ b/org/testdata/keywords.org
@@ -20,3 +20,6 @@ named paragraph
 #+begin_src
 named block
 #+end_src
+
+# comments must have whitespace after the hashtag
+#not a comment because there's no space after the hashtag
diff --git a/org/testdata/keywords.pretty_org b/org/testdata/keywords.pretty_org
index 7b0bf23..2e309eb 100644
--- a/org/testdata/keywords.pretty_org
+++ b/org/testdata/keywords.pretty_org
@@ -20,3 +20,6 @@ named paragraph
 #+BEGIN_SRC
 named block
 #+END_SRC
+
+# comments must have whitespace after the hashtag
+#not a comment because there's no space after the hashtag