diff --git a/unittests/AST/CommentLexer.cpp b/unittests/AST/CommentLexer.cpp
index 2ec741b..cc4535a 100644
--- a/unittests/AST/CommentLexer.cpp
+++ b/unittests/AST/CommentLexer.cpp
@@ -322,7 +322,35 @@
   }
 }
 
+// A command marker followed by a non-letter that is not a part of an escape
+// sequence.
 TEST_F(CommentLexerTest, DoxygenCommand5) {
+  const char *Source = "/// \\^ \\0";
+  std::vector<Token> Toks;
+
+  lexString(Source, Toks);
+
+  ASSERT_EQ(6U, Toks.size());
+
+  ASSERT_EQ(tok::text,       Toks[0].getKind());
+  ASSERT_EQ(StringRef(" "),  Toks[0].getText());
+
+  ASSERT_EQ(tok::text,       Toks[1].getKind());
+  ASSERT_EQ(StringRef("\\"), Toks[1].getText());
+
+  ASSERT_EQ(tok::text,       Toks[2].getKind());
+  ASSERT_EQ(StringRef("^ "), Toks[2].getText());
+
+  ASSERT_EQ(tok::text,       Toks[3].getKind());
+  ASSERT_EQ(StringRef("\\"), Toks[3].getText());
+
+  ASSERT_EQ(tok::text,       Toks[4].getKind());
+  ASSERT_EQ(StringRef("0"),  Toks[4].getText());
+
+  ASSERT_EQ(tok::newline,    Toks[5].getKind());
+}
+
+TEST_F(CommentLexerTest, DoxygenCommand6) {
   const char *Source = "/// \\brief Aaa.";
   std::vector<Token> Toks;
 
@@ -342,7 +370,7 @@
   ASSERT_EQ(tok::newline,       Toks[3].getKind());
 }
 
-TEST_F(CommentLexerTest, DoxygenCommand6) {
+TEST_F(CommentLexerTest, DoxygenCommand7) {
   const char *Source = "/// \\em\\em \\em\t\\em\n";
   std::vector<Token> Toks;
 
@@ -374,7 +402,7 @@
   ASSERT_EQ(tok::newline,    Toks[7].getKind());
 }
 
-TEST_F(CommentLexerTest, DoxygenCommand7) {
+TEST_F(CommentLexerTest, DoxygenCommand8) {
   const char *Source = "/// \\aaa\\bbb \\ccc\t\\ddd\n";
   std::vector<Token> Toks;
 
@@ -406,7 +434,7 @@
   ASSERT_EQ(tok::newline,     Toks[7].getKind());
 }
 
-TEST_F(CommentLexerTest, DoxygenCommand8) {
+TEST_F(CommentLexerTest, DoxygenCommand9) {
   const char *Source = "// \\c\n";
   std::vector<Token> Toks;