diff --git a/src/lint/engine/PhutilLintEngine.php b/src/lint/engine/PhutilLintEngine.php
index 97d9232d..39c25780 100644
--- a/src/lint/engine/PhutilLintEngine.php
+++ b/src/lint/engine/PhutilLintEngine.php
@@ -92,6 +92,8 @@ class PhutilLintEngine extends ArcanistLintEngine {
           => ArcanistLintSeverity::SEVERITY_WARNING,
         ArcanistXHPASTLinter::LINT_PHP_53_FEATURES
           => ArcanistLintSeverity::SEVERITY_ERROR,
+        ArcanistXHPASTLinter::LINT_COMMENT_SPACING
+          => ArcanistLintSeverity::SEVERITY_ERROR,
       ));
     $linters[] = $xhpast_linter;
     foreach ($paths as $path) {
diff --git a/src/lint/linter/ArcanistXHPASTLinter.php b/src/lint/linter/ArcanistXHPASTLinter.php
index e34a7f68..8e1e1c85 100644
--- a/src/lint/linter/ArcanistXHPASTLinter.php
+++ b/src/lint/linter/ArcanistXHPASTLinter.php
@@ -57,6 +57,7 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
   const LINT_PHP_53_FEATURES           = 31;
   const LINT_REUSED_AS_ITERATOR        = 32;
   const LINT_PHT_WITH_DYNAMIC_STRING   = 33;
+  const LINT_COMMENT_SPACING           = 34;
 
 
   public function getLintNameMap() {
@@ -93,6 +94,7 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
       self::LINT_PHP_53_FEATURES           => 'Use Of PHP 5.3 Features',
       self::LINT_REUSED_AS_ITERATOR        => 'Variable Reused As Iterator',
       self::LINT_PHT_WITH_DYNAMIC_STRING   => 'Use of pht() on Dynamic String',
+      self::LINT_COMMENT_SPACING           => 'Comment Spaces',
     );
   }
 
@@ -124,6 +126,9 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
       self::LINT_PHT_WITH_DYNAMIC_STRING
         => ArcanistLintSeverity::SEVERITY_WARNING,
 
+      self::LINT_COMMENT_SPACING
+        => ArcanistLintSeverity::SEVERITY_ADVICE,
+
       // This is disabled by default because it implies a very strict policy
       // which isn't necessary in the general case.
       self::LINT_RAGGED_CLASSTREE_EDGE
@@ -194,6 +199,7 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
     $this->lintPregQuote($root);
     $this->lintUndeclaredVariables($root);
     $this->lintArrayIndexWhitespace($root);
+    $this->lintCommentSpaces($root);
     $this->lintHashComments($root);
     $this->lintPrimaryDeclarationFilenameMatch($root);
     $this->lintTautologicalExpressions($root);
@@ -567,6 +573,24 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
   }
 
 
+  protected function lintCommentSpaces($root) {
+    foreach ($root->selectTokensOfType('T_COMMENT') as $comment) {
+      $value = $comment->getValue();
+      if ($value[0] != '#') {
+        $match = null;
+        if (preg_match('@^(/[/*]+)[^/*\s]@', $value, $match)) {
+          $this->raiseLintAtOffset(
+            $comment->getOffset(),
+            self::LINT_COMMENT_SPACING,
+            'Put space after comment start.',
+            $match[1],
+            $match[1].' ');
+        }
+      }
+    }
+  }
+
+
   protected function lintHashComments($root) {
     foreach ($root->selectTokensOfType('T_COMMENT') as $comment) {
       $value = $comment->getValue();
@@ -579,7 +603,7 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
         self::LINT_COMMENT_STYLE,
         'Use "//" single-line comments, not "#".',
         '#',
-        '//');
+        (preg_match('/^#\S/', $value) ? '// ' : '//'));
     }
   }
 
diff --git a/src/lint/linter/__tests__/xhpast/hash-comments.lint-test b/src/lint/linter/__tests__/xhpast/hash-comments.lint-test
index 3c5d700d..c4853f5a 100644
--- a/src/lint/linter/__tests__/xhpast/hash-comments.lint-test
+++ b/src/lint/linter/__tests__/xhpast/hash-comments.lint-test
@@ -12,23 +12,42 @@
  */
 //#yes
 /*#yes*/
+#
+//
+/////////////////// yes
+/*no */
+/**no */
+/** yes */
+/**** yes ****/
 ~~~~~~~~~~
 error:2:1
 error:3:1
 error:5:1
 error:6:11
+advice:13:1
+advice:14:1
+error:15:1
+advice:18:1
+advice:19:1
 ~~~~~~~~~~
 <?php
 // no
-//no
+// no
 // yes
 // no
-/* yes */ //no
+/* yes */ // no
 /*
  * yes
  */
 /**
  * yes
  */
-//#yes
-/*#yes*/
+// #yes
+/* #yes*/
+//
+//
+/////////////////// yes
+/* no */
+/** no */
+/** yes */
+/**** yes ****/