diff --git a/src/lib/uTop_complete.cppo.ml b/src/lib/uTop_complete.cppo.ml
index 6c13d8a..bdeaeaa 100644
--- a/src/lib/uTop_complete.cppo.ml
+++ b/src/lib/uTop_complete.cppo.ml
@@ -74,7 +74,7 @@ let parse_longident tokens =
              | l -> Some (longident_of_list l))
   in
   match tokens with
-    | ((Comment (_, false) | String false | Quotation (_, false)), _) :: _ ->
+    | ((Comment (_, false) | String (_, false) | Quotation (_, false)), _) :: _ ->
         (* An unterminated command, string, or quotation. *)
         None
     | ((Uident id | Lident id), { idx1 = start }) :: tokens ->
@@ -847,23 +847,23 @@ let complete ~syntax ~phrase_terminator ~input =
         (start, lookup_assoc src (list_directives phrase_terminator))
 
     (* Complete with ";;" when possible. *)
-    | [(Symbol "#", _); ((Lident _ | Uident _), _); (String true, { idx2 = stop })]
-    | [(Symbol "#", _); ((Lident _ | Uident _), _); (String true, _); (Blanks, { idx2 = stop })] ->
+    | [(Symbol "#", _); ((Lident _ | Uident _), _); (String (_, true), { idx2 = stop })]
+    | [(Symbol "#", _); ((Lident _ | Uident _), _); (String (_, true), _); (Blanks, { idx2 = stop })] ->
         (stop, [(phrase_terminator, "")])
-    | [(Symbol "#", _); ((Lident _ | Uident _), _); (String true, _); (Symbol sym, { idx1 = start })] ->
+    | [(Symbol "#", _); ((Lident _ | Uident _), _); (String (_, true), _); (Symbol sym, { idx1 = start })] ->
         if Zed_utf8.starts_with phrase_terminator sym then
           (start, [(phrase_terminator, "")])
         else
           (0, [])
 
     (* Completion on #require. *)
-    | [(Symbol "#", _); (Lident "require", _); (String false, loc)] ->
-        let pkg = String.sub input (loc.ofs1 + 1) (String.length input - loc.ofs1 - 1) in
+    | [(Symbol "#", _); (Lident "require", _); (String (tlen, false), loc)] ->
+        let pkg = String.sub input (loc.ofs1 + tlen) (String.length input - loc.ofs1 - tlen) in
         let pkgs = lookup pkg (Fl_package_base.list_packages ()) in
         (loc.idx1 + 1, List.map (fun pkg -> (pkg, "\"" ^ phrase_terminator)) (List.sort compare pkgs))
 
-    | [(Symbol "#", _); (Lident "typeof", _); (String false, loc)] ->
-      let prefix = String.sub input (loc.ofs1 + 1) (String.length input - loc.ofs1 - 1) in
+    | [(Symbol "#", _); (Lident "typeof", _); (String (tlen, false), loc)] ->
+      let prefix = String.sub input (loc.ofs1 + tlen) (String.length input - loc.ofs1 - tlen) in
       begin match Longident.parse prefix with
       | Longident.Ldot (lident, last_prefix) ->
         let set = names_of_module lident in
@@ -877,8 +877,8 @@ let complete ~syntax ~phrase_terminator ~input =
       end
 
     (* Completion on #load. *)
-    | [(Symbol "#", _); (Lident ("load" | "load_rec"), _); (String false, loc)] ->
-        let file = String.sub input (loc.ofs1 + 1) (String.length input - loc.ofs1 - 1) in
+    | [(Symbol "#", _); (Lident ("load" | "load_rec"), _); (String (tlen, false), loc)] ->
+        let file = String.sub input (loc.ofs1 + tlen) (String.length input - loc.ofs1 - tlen) in
         let filter name = Filename.check_suffix name ".cma" || Filename.check_suffix name ".cmo" in
         let map =
           if Filename.is_relative file then
@@ -898,8 +898,8 @@ let complete ~syntax ~phrase_terminator ~input =
 
 #if OCAML_VERSION >= (4, 02, 0)
     (* Completion on #ppx. *)
-    | [(Symbol "#", _); (Lident ("ppx"), _); (String false, loc)] ->
-        let file = String.sub input (loc.ofs1 + 1) (String.length input - loc.ofs1 - 1) in
+    | [(Symbol "#", _); (Lident ("ppx"), _); (String (tlen, false), loc)] ->
+        let file = String.sub input (loc.ofs1 + tlen) (String.length input - loc.ofs1 - tlen) in
         let filter ~dir_ok name =
           try
             Unix.access name [Unix.X_OK];
@@ -928,8 +928,8 @@ let complete ~syntax ~phrase_terminator ~input =
 #endif
 
     (* Completion on #use. *)
-    | [(Symbol "#", _); (Lident "use", _); (String false, loc)] ->
-        let file = String.sub input (loc.ofs1 + 1) (String.length input - loc.ofs1 - 1) in
+    | [(Symbol "#", _); (Lident "use", _); (String (tlen, false), loc)] ->
+        let file = String.sub input (loc.ofs1 + tlen) (String.length input - loc.ofs1 - tlen) in
         let filter name =
           match try Some (String.rindex name '.') with Not_found -> None with
             | None ->
@@ -955,8 +955,8 @@ let complete ~syntax ~phrase_terminator ~input =
          List.map (function (w, Directory) -> (w, "") | (w, File) -> (w, "\"" ^ phrase_terminator)) result)
 
     (* Completion on #directory and #cd. *)
-    | [(Symbol "#", _); (Lident ("cd" | "directory"), _); (String false, loc)] ->
-        let file = String.sub input (loc.ofs1 + 1) (String.length input - loc.ofs1 - 1) in
+    | [(Symbol "#", _); (Lident ("cd" | "directory"), _); (String (tlen, false), loc)] ->
+        let file = String.sub input (loc.ofs1 + tlen) (String.length input - loc.ofs1 - tlen) in
         let list = list_directories (Filename.dirname file) in
         let name = basename file in
         let result = lookup name list in
diff --git a/src/lib/uTop_lexer.mll b/src/lib/uTop_lexer.mll
index 9edb25f..6706201 100644
--- a/src/lib/uTop_lexer.mll
+++ b/src/lib/uTop_lexer.mll
@@ -117,7 +117,13 @@ rule tokens syntax context idx acc = parse
       { let ofs = lexeme_start lexbuf in
         let idx2, terminated = string (idx + 1) lexbuf in
         let loc = mkloc idx idx2 ofs (lexeme_end lexbuf) in
-        tokens syntax context idx2 ((String terminated, loc) :: acc) lexbuf }
+        tokens syntax context idx2 ((String (1, terminated), loc) :: acc) lexbuf }
+  | '{' (lowercase* as tag) '|'
+      { let ofs = lexeme_start lexbuf in
+        let delim_len = String.length tag + 2 in
+        let idx2, terminated = quoted_string (idx + delim_len) tag lexbuf in
+        let loc = mkloc idx idx2 ofs (lexeme_end lexbuf) in
+        tokens syntax context idx2 ((String (delim_len, terminated), loc) :: acc) lexbuf }
   | "'" [^'\'' '\\'] "'"
   | "'\\" ['\\' '"' 'n' 't' 'b' 'r' ' ' '\'' 'x' '0'-'9'] eof
   | "'\\" ['\\' '"' 'n' 't' 'b' 'r' ' ' '\''] "'"
@@ -217,6 +223,18 @@ and string idx = parse
   | eof
       { (idx, false) }
 
+and quoted_string idx tag = parse
+    | '|' (lowercase* as tag2) '}'
+        { let idx = idx + 2 + String.length tag2 in
+          if tag = tag2 then
+            (idx, true)
+          else
+            quoted_string idx tag lexbuf }
+    | eof
+        { (idx, false) }
+    | uchar
+        { quoted_string (idx + 1) tag lexbuf }
+
 and quotation syntax depth idx1 idx2 ofs1 = parse
   | '<' (':' ident)? ('@' lident)? '<'
       { quotation syntax (depth + 1) idx1 (idx2 + lexeme_size lexbuf) ofs1 lexbuf }
diff --git a/src/lib/uTop_token.ml b/src/lib/uTop_token.ml
index b077c26..57d948c 100644
--- a/src/lib/uTop_token.ml
+++ b/src/lib/uTop_token.ml
@@ -30,8 +30,8 @@ type t =
   | Uident of string
   | Constant of string
   | Char
-  | String of bool
-      (** [String terminated]. *)
+  | String of int * bool
+      (** [String (quote_size, terminated)]. *)
   | Comment of comment_kind * bool
       (** [Comment (kind, terminated)]. *)
   | Blanks