diff --git a/doc/doc-primitives.saty b/doc/doc-primitives.saty
index 360f77f89..d6be2d014 100644
--- a/doc/doc-primitives.saty
+++ b/doc/doc-primitives.saty
@@ -299,7 +299,7 @@ document (|
       }
       +command (`regexp-of-string`) (tS --> tRE) {
         \code{regexp-of-string ${s}}で文字列から正規表現型を生成する．
-        使える正規表現の構文はOCamlの\code{Str.regexp}で使えるものと等しい．
+        使える正規表現の構文はPCREと等しい．
         正規表現として不適当な文字列が与えられた場合は実行時エラーが出る．
       }
       +command (`string-scan`) (tRE --> (tS --> (tOPT (tPROD [tS; tS])))) {
diff --git a/satysfi.opam b/satysfi.opam
index 34dbf90e3..9fc8bac26 100644
--- a/satysfi.opam
+++ b/satysfi.opam
@@ -31,7 +31,7 @@ depends: [
   "ocamlfind" {build}
   "otfm" {= "0.3.7+satysfi"}
   "ppx_deriving"
-  "re" {build}
+  "pcre" {>= "7.4.0" & < "7.5.0"}
   "uutf"
   "yojson-with-position" {= "1.4.2+satysfi"}
   "omd" {< "2.0.0~"}
diff --git a/src/dune b/src/dune
index 520ef49dd..975828ed6 100644
--- a/src/dune
+++ b/src/dune
@@ -14,6 +14,7 @@
             uutf
             yojson-with-position
             omd
+            pcre
             )
  (preprocess (pps
               ppx_deriving.show
diff --git a/src/frontend/evalUtil.ml b/src/frontend/evalUtil.ml
index 74de415f4..95f447bd8 100644
--- a/src/frontend/evalUtil.ml
+++ b/src/frontend/evalUtil.ml
@@ -420,7 +420,7 @@ let get_float value : float =
   | _                         -> report_bug_value "get_float" value
 
 
-let get_regexp (value : syntactic_value) : Str.regexp =
+let get_regexp (value : syntactic_value) : Pcre.regexp =
   match value with
   | BaseConstant(BCRegExp(regexp)) -> regexp
   | _                              -> report_bug_value "get_regexp" value
diff --git a/src/frontend/types.cppo.ml b/src/frontend/types.cppo.ml
index 0a916d49e..bfcd16880 100644
--- a/src/frontend/types.cppo.ml
+++ b/src/frontend/types.cppo.ml
@@ -641,7 +641,7 @@ type base_constant =
   | BCFloat    of float
   | BCLength   of length
   | BCString   of string
-  | BCRegExp   of Str.regexp
+  | BCRegExp   of Pcre.regexp
       [@printer (fun fmt _ -> Format.fprintf fmt "<regexp>")]
   | BCPath     of path list
       [@printer (fun fmt _ -> Format.fprintf fmt "<path>")]
diff --git a/tools/gencode/dune b/tools/gencode/dune
index af6c3c16e..f1775488b 100644
--- a/tools/gencode/dune
+++ b/tools/gencode/dune
@@ -1,5 +1,5 @@
 (executable
  (name gencode)
- (libraries core_kernel re)
+ (libraries core_kernel pcre)
  ;; (preprocess (pps (ppx_driver.runner)))
  )
diff --git a/tools/gencode/u.ml b/tools/gencode/u.ml
index f5daa1122..36dec13b6 100644
--- a/tools/gencode/u.ml
+++ b/tools/gencode/u.ml
@@ -5,24 +5,13 @@ let default v = function
 
 
 let trim_re =
-  let open Re in
-  let sp = alt [ char ' '; char '\t' ] in
-  let nl = alt [ str "\r\n"; char '\r'; char '\n' ] in
-  (* -- /\A *\n(.*\n) *\z/ -- *)
-  seq [
-    bos;
-    rep sp;
-    nl;
-    group @@ seq [ rep any; nl ];
-    rep sp;
-    eos;
-  ] |> compile
+  Pcre.regexp ~flags:[`UTF8; `DOTALL] "\\A *\n(.*\n) *\\z"
 
 
 let trim s =
-  match Re.exec_opt trim_re s with
-  | Some(gr) -> Re.Group.get gr 1
-  | None     -> s
+  match Pcre.exec ~rex:trim_re s with
+  | exception Not_found -> s
+  | substrings -> Pcre.get_substring substrings 1
 
 
 let opt_map f = function
diff --git a/tools/gencode/vminst.ml b/tools/gencode/vminst.ml
index f8bfe008b..938930cb4 100644
--- a/tools/gencode/vminst.ml
+++ b/tools/gencode/vminst.ml
@@ -1965,12 +1965,13 @@ make_int (String.length str)
         ~is_pdf_mode_primitive:true
         ~is_text_mode_primitive:true
         ~code:{|
-if Str.string_match pat str 0 then
-  let matched = Str.matched_string str in
-  let start   = String.length matched in
+match Pcre.exec ~flags:[`ANCHORED] ~rex:pat str with
+| substrings ->
+  let _, start = Pcre.get_substring_ofs substrings 0 in
+  let matched = String.sub str 0 start in
   let rest    = String.sub str start (String.length str - start) in
   Constructor("Some", Tuple([make_string matched; make_string rest]))
-else
+| exception Not_found ->
   Constructor("None", const_unit)
 |}
     ; inst "PrimitiveStringUnexplode"
@@ -2019,8 +2020,12 @@ make_list make_int ilst
         ~is_text_mode_primitive:true
         ~code:{|
 let regexp =
-  try Str.regexp str with
-  | Failure(msg) -> report_dynamic_error ("regexp-of-string: " ^ msg)
+  match Pcre.regexp ~flags:[`UTF8] str with
+  | re -> re
+  | exception Pcre.Error(Pcre.BadPattern (msg, pos)) ->
+    report_dynamic_error ("regexp-of-string: " ^ msg)
+  | exception Pcre.Error(Pcre.InternalError msg) ->
+    report_dynamic_error ("regexp-of-string: " ^ msg)
 in
 make_regexp regexp
 |}
@@ -2030,13 +2035,13 @@ make_regexp regexp
         ~fields:[
         ]
         ~params:[
-          param "pat" ~type_:"regexp";
+          param "rex" ~type_:"regexp";
           param "s" ~type_:"string";
         ]
         ~is_pdf_mode_primitive:true
         ~is_text_mode_primitive:true
         ~code:{|
-make_bool (Str.string_match pat s 0)
+make_bool (Pcre.pmatch ~flags:[`ANCHORED] ~rex s)
 |}
     ; inst "PrimitiveSplitIntoLines"
         ~name:"split-into-lines"
@@ -2065,7 +2070,7 @@ pairlst |> make_list (fun (i, s) -> Tuple([make_int i; make_string s]))
         ~is_pdf_mode_primitive:true
         ~is_text_mode_primitive:true
         ~code:{|
-let slst = Str.split sep str in
+let slst = Pcre.split ~rex:sep str in
 let pairlst = slst |> List.map chop_space_indent in
 pairlst |> make_list (fun (i, s) -> Tuple([make_int i; make_string s]))
 |}