diff --git a/src/compiler/GF/Command/Commands.hs b/src/compiler/GF/Command/Commands.hs
index d000b35b0..9ea5cb6e0 100644
--- a/src/compiler/GF/Command/Commands.hs
+++ b/src/compiler/GF/Command/Commands.hs
@@ -847,7 +847,7 @@ pgfCommands = Map.fromList [
    prGrammar pgf opts
      | isOpt "pgf"      opts = do
           let outfile = valStrOpts "file" (abstractName pgf ++ ".pgf") opts
-          restricted $ writePGF outfile pgf
+          restricted $ writePGF outfile pgf (Just (map concreteName (optLangs pgf opts)))
           putStrLn $ "wrote file " ++ outfile
           return void
      | isOpt "cats"     opts = return $ fromString $ unwords $ categories pgf
diff --git a/src/compiler/GF/Compiler.hs b/src/compiler/GF/Compiler.hs
index 92b207900..9e8b6cb07 100644
--- a/src/compiler/GF/Compiler.hs
+++ b/src/compiler/GF/Compiler.hs
@@ -180,7 +180,7 @@ writeGrammar :: Options -> PGF -> IOE ()
 writeGrammar opts pgf =
   if fst (flag optLinkTargets opts)
     then do let outfile = outputPath opts (grammarName opts pgf <.> "pgf")
-            writing opts outfile (writePGF outfile pgf)
+            writing opts outfile (writePGF outfile pgf Nothing)
     else return ()
 
 writeOutput :: Options -> FilePath-> String -> IOE ()
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index f2230d3b9..95959b4d5 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -244,6 +244,7 @@ void pgf_merge_pgf(PgfDB *db, PgfRevision revision,
 PGF_API
 void pgf_write_pgf(const char* fpath,
                    PgfDB *db, PgfRevision revision,
+                   PgfText **langs,
                    PgfExn* err)
 {
     FILE *out = NULL;
@@ -258,7 +259,7 @@ void pgf_write_pgf(const char* fpath,
             DB_scope scope(db, READER_SCOPE);
             ref<PgfPGF> pgf = db->revision2pgf(revision);
 
-            PgfWriter wtr(out);
+            PgfWriter wtr(langs, out);
             wtr.write_pgf(pgf);
         }
     } PGF_API_END
diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index 06776570c..56b5b3ed9 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -287,6 +287,7 @@ void pgf_merge_pgf(PgfDB *db, PgfRevision revision,
 PGF_API_DECL
 void pgf_write_pgf(const char* fpath,
                    PgfDB *db, PgfRevision revision,
+                   PgfText **langs, // null terminated list or null
                    PgfExn* err);
 
 PGF_API_DECL
diff --git a/src/runtime/c/pgf/writer.cxx b/src/runtime/c/pgf/writer.cxx
index 8b20495e0..3ef32ec4d 100644
--- a/src/runtime/c/pgf/writer.cxx
+++ b/src/runtime/c/pgf/writer.cxx
@@ -2,9 +2,10 @@
 #include "data.h"
 #include "writer.h"
 
-PgfWriter::PgfWriter(FILE *out)
+PgfWriter::PgfWriter(PgfText **langs, FILE *out)
 {
     this->out = out;
+    this->langs = langs;
     this->abstract = 0;
 }
 
@@ -411,6 +412,22 @@ void PgfWriter::write_printname(ref<PgfConcrPrintname> printname)
 
 void PgfWriter::write_concrete(ref<PgfConcr> concr)
 {
+    if (langs != NULL) {
+        bool found = false;
+        PgfText** p = langs;
+        while (*p) {
+            if (textcmp(*p, &concr->name) == 0) {
+                found = true;
+                break;
+            }
+            p++;
+        }
+
+        if (!found) {
+            return;
+        }
+    }
+
 	seq_ids.start(concr);
 
     write_name(&concr->name);
@@ -431,5 +448,16 @@ void PgfWriter::write_pgf(ref<PgfPGF> pgf)
     write_namespace<PgfFlag>(pgf->gflags, &PgfWriter::write_flag);
 
     write_abstract(ref<PgfAbstr>::from_ptr(&pgf->abstract));
-    write_namespace<PgfConcr>(pgf->concretes, &PgfWriter::write_concrete);
+
+    if (langs == NULL)
+        write_len(namespace_size(pgf->concretes));
+    else {
+        size_t len = 0;
+        PgfText** p = langs;
+        while (*p) {
+            len++; p++;
+        }
+        write_len(len);
+    }
+    write_namespace_helper<PgfConcr>(pgf->concretes, &PgfWriter::write_concrete);
 }
diff --git a/src/runtime/c/pgf/writer.h b/src/runtime/c/pgf/writer.h
index ab7400ec8..c596b1fb5 100644
--- a/src/runtime/c/pgf/writer.h
+++ b/src/runtime/c/pgf/writer.h
@@ -4,7 +4,7 @@
 class PGF_INTERNAL_DECL PgfWriter
 {
 public:
-    PgfWriter(FILE *out);
+    PgfWriter(PgfText **langs, FILE *out);
 
     void write_uint8(uint8_t b);
     void write_u16be(uint16_t u);
@@ -66,6 +66,7 @@ private:
     void write_presult(ref<ref<PgfPResult>> r) { write_presult(*r); };
 
     FILE *out;
+    PgfText **langs;
 
     ref<PgfAbstr> abstract;
     PgfPhrasetableIds seq_ids;
diff --git a/src/runtime/haskell/PGF2.hsc b/src/runtime/haskell/PGF2.hsc
index 5e5f21d48..982cc24ff 100644
--- a/src/runtime/haskell/PGF2.hsc
+++ b/src/runtime/haskell/PGF2.hsc
@@ -188,11 +188,15 @@ newNGF abs_name mb_fpath =
     fptr <- newForeignPtrEnv pgf_free_revision c_db c_revision
     return (PGF c_db fptr Map.empty)
 
-writePGF :: FilePath -> PGF -> IO ()
-writePGF fpath p =
+writePGF :: FilePath -> PGF -> Maybe [ConcName] -> IO ()
+writePGF fpath p mb_langs =
   withCString fpath $ \c_fpath ->
   withForeignPtr (a_revision p) $ \c_revision ->
-    withPgfExn "writePGF" (pgf_write_pgf c_fpath (a_db p) c_revision)
+  maybe (\f -> f nullPtr) (withLangs []) mb_langs $ \c_langs ->
+    withPgfExn "writePGF" (pgf_write_pgf c_fpath (a_db p) c_revision c_langs)
+  where
+    withLangs clangs []           f = withArray0 nullPtr (reverse clangs) f
+    withLangs clangs (lang:langs) f = withText lang $ \clang -> withLangs (clang:clangs) langs f
 
 showPGF :: PGF -> String
 showPGF p =
diff --git a/src/runtime/haskell/PGF2/FFI.hsc b/src/runtime/haskell/PGF2/FFI.hsc
index 07e3db8b2..74fb8ca91 100644
--- a/src/runtime/haskell/PGF2/FFI.hsc
+++ b/src/runtime/haskell/PGF2/FFI.hsc
@@ -78,7 +78,7 @@ foreign import ccall pgf_new_ngf :: Ptr PgfText -> CString -> Ptr (Ptr PGF) -> P
 
 foreign import ccall pgf_merge_pgf :: Ptr PgfDB -> Ptr PGF -> CString -> Ptr PgfExn -> IO ()
 
-foreign import ccall pgf_write_pgf :: CString -> Ptr PgfDB -> Ptr PGF -> Ptr PgfExn -> IO ()
+foreign import ccall pgf_write_pgf :: CString -> Ptr PgfDB -> Ptr PGF -> Ptr (Ptr PgfText) -> Ptr PgfExn -> IO ()
 
 foreign import ccall "pgf_free_revision" pgf_free_revision_ :: Ptr PgfDB -> Ptr PGF -> IO ()
 
diff --git a/src/runtime/python/pypgf.c b/src/runtime/python/pypgf.c
index c5a06dffb..901105d31 100644
--- a/src/runtime/python/pypgf.c
+++ b/src/runtime/python/pypgf.c
@@ -517,18 +517,45 @@ PGF_dealloc(PGFObject *self)
 }
 
 static PyObject *
-PGF_writePGF(PGFObject *self, PyObject *args)
+PGF_writePGF(PGFObject *self, PyObject *args, PyObject *kwargs)
 {
+    char *kwds[] = {"","langs",NULL};
+
     const char *fpath;
-    if (!PyArg_ParseTuple(args, "s", &fpath))
+    PyObject *py_langs = NULL;
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s|O!", &kwds[0], &fpath, &PyList_Type, &py_langs))
         return NULL;
 
+    PgfText **langs = NULL;
+    if (py_langs != NULL) {
+        size_t len = PyList_Size(py_langs);
+        langs = (PgfText **) alloca((len+1)*sizeof(PgfText*));
+        for (size_t i = 0; i < len; i++) {
+            langs[i] = PyUnicode_AsPgfText(PyList_GetItem(py_langs,i));
+            if (!langs[i]) {
+                while (i > 0) {
+                    FreePgfText(langs[--i]);
+                }
+                return NULL;
+            }
+        }
+        langs[len] = NULL;
+    }
+
     PgfExn err;
-    pgf_write_pgf(fpath, self->db, self->revision, &err);
+    pgf_write_pgf(fpath, self->db, self->revision, langs, &err);
     if (handleError(err) != PGF_EXN_NONE) {
         return NULL;
     }
 
+    if (langs != NULL) {
+        PgfText **p = langs;
+        while (*p) {
+            FreePgfText(*p);
+            p++;
+        }
+    }
+
     Py_RETURN_NONE;
 }
 
@@ -1152,7 +1179,7 @@ PGF_embed(PGFObject* self, PyObject *modname)
 #endif
 
 static PyMethodDef PGF_methods[] = {
-    {"writePGF", (PyCFunction)PGF_writePGF, METH_VARARGS,
+    {"writePGF", (PyCFunction)PGF_writePGF, METH_VARARGS | METH_KEYWORDS,
      "Writes to a PGF file"},
     {"categoryContext", (PyCFunction)PGF_categoryContext, METH_VARARGS,
      "Returns the context for a given category"