diff --git a/pollen/private/pipe.py b/pollen/private/pipe.py
index 034c21e..98c4643 100644
--- a/pollen/private/pipe.py
+++ b/pollen/private/pipe.py
@@ -2,6 +2,7 @@
 # continuously. Input format is:
 #
 #     <lexer-name>
+#     <list-of-highlighted-lines>
 #     <code>
 #     ...
 #     __END__
@@ -28,12 +29,9 @@ parser.add_option('--linenos', action="store_true", dest="linenos")
 parser.add_option('--cssclass', default="source", dest="cssclass")
 (options, _) = parser.parse_args()
 
-formatter = HtmlFormatter(linenos=options.linenos,
-                          cssclass=options.cssclass,
-                          encoding="utf-8")
-
 lexer = ""
 code = ""
+lines-to-highlight = ""
 py_version = sys.version_info.major
 sys.stdout.write("ready\n")
 sys.stdout.flush()
@@ -47,6 +45,10 @@ while 1:
         break
     elif line == '__END__':
         # Lex input finished. Lex it.
+        formatter = HtmlFormatter(linenos=options.linenos,
+                          cssclass=options.cssclass,
+                          encoding="utf-8",
+                          hl_lines=lines-to-highlight)
         if py_version >= 3:
           sys.stdout.write(highlight(code, lexer, formatter).decode("utf-8"))
         else:
@@ -55,12 +57,17 @@ while 1:
         sys.stdout.flush()
         lexer = ""
         code = ""
+        lines-to-highlight = ""
     elif lexer == "":
         # Starting another lex. First line is the lexer name.
         try:
             lexer = get_lexer_by_name(line, encoding="guess")
         except ClassNotFound:
             lexer = get_lexer_by_name("text", encoding="guess")
+    elif lines-to-highlight == "":
+        # Starting another lex. Second line is list of lines to highlight,
+        # formatted as string of whitespace-separated integers
+        lines-to-highlight = [int(str) for str in line.split()]
     else:
         # Accumulate more code
         # Use `line_raw`: Do want trailing space, \n, \r
diff --git a/pollen/private/ts.rktd b/pollen/private/ts.rktd
index 6c03fde..affbdba 100644
--- a/pollen/private/ts.rktd
+++ b/pollen/private/ts.rktd
@@ -1 +1 @@
-1488121531
+1488160788
diff --git a/pollen/unstable/pygments.rkt b/pollen/unstable/pygments.rkt
index c213d9d..d765ba9 100644
--- a/pollen/unstable/pygments.rkt
+++ b/pollen/unstable/pygments.rkt
@@ -128,13 +128,15 @@ if zero is False:
      (stop)
      (old-exit-handler v))))
 
-(define (pygmentize code lang) ;; string? string? -> (listof xexpr?)
+(define (pygmentize code lang [hl-lines null]) ;; string? string? (listof number?) -> (listof xexpr?)
   (define (default code)
     `((pre () (code () ,code))))
   (unless (running?)
     (start))
   (cond [(running?)
+         ;; order of writing arguments is significant: cooperates with pipe.py
          (displayln lang pyg-out)
+         (displayln (string-join (map number->string hl-lines) " ") pyg-out)
          (displayln code pyg-out)
          (displayln "__END__" pyg-out)
          (let loop ([s ""])
@@ -149,10 +151,11 @@ if zero is False:
 ;;;;;;;;;;;;;;;;;;
 
 
-(define (highlight lang . codelines)
+(define (highlight #:lines [hl-lines null]
+                   lang . codelines)
   (define code (string-append* codelines))
   `(div ((class "highlight"))
-      ,@(strip-empty-attrs (pygmentize code lang))))
+      ,@(strip-empty-attrs (pygmentize code lang hl-lines))))
 
 ;; Other CSS options available from http://richleland.github.io/pygments-css/