diff --git a/CHANGES b/CHANGES
index 2f6fd3b..5fd7498 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2,6 +2,7 @@
 =====
 * Use generational global roots to protect
   encoder and decoder callbacks.
+* Harness more global roots.
 
 0.5.0 (2023-09-05)
 =====
diff --git a/flac.opam b/flac.opam
index ca2efde..dd3fbdd 100644
--- a/flac.opam
+++ b/flac.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.5.0"
+version: "0.5.1"
 synopsis: "Bindings to libflac"
 maintainer: ["The Savonet Team <savonet-users@lists.sourceforge.net>"]
 authors: ["The Savonet Team <savonet-users@lists.sourceforge.net>"]
diff --git a/src/flac_stubs.c b/src/flac_stubs.c
index d780cc3..02f2e69 100644
--- a/src/flac_stubs.c
+++ b/src/flac_stubs.c
@@ -357,19 +357,25 @@ FLAC__StreamDecoderReadStatus static dec_read_callback(
   caml_acquire_runtime_system();
 
   int readlen = *bytes;
-  value data = caml_alloc_string(readlen);
 
+  value data = Val_unit;
+  value ret = Val_unit;
   caml_register_generational_global_root(&data);
+  caml_register_generational_global_root(&ret);
 
-  value ret = caml_callback3_exn(Dec_read(callbacks->callbacks), data,
-                                 Val_int(0), Val_int(readlen));
+  data = caml_alloc_string(readlen);
+
+  ret = caml_callback3_exn(Dec_read(callbacks->callbacks), data, Val_int(0),
+                           Val_int(readlen));
 
   if (Is_exception_result(ret)) {
     caml_remove_generational_global_root(&data);
+    caml_remove_generational_global_root(&ret);
     caml_raise(Extract_exception(ret));
   }
 
   caml_remove_generational_global_root(&data);
+  caml_remove_generational_global_root(&ret);
 
   memcpy(buffer, String_val(data), Int_val(ret));
   *bytes = Int_val(ret);
@@ -407,9 +413,12 @@ dec_write_callback(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame,
   ocaml_flac_register_thread();
   caml_acquire_runtime_system();
 
-  value data = caml_alloc_tuple(channels);
-
+  value data = Val_unit;
+  value ret = Val_unit;
   caml_register_generational_global_root(&data);
+  caml_register_generational_global_root(&ret);
+
+  data = caml_alloc_tuple(channels);
 
   int c, i;
   for (c = 0; c < channels; c++) {
@@ -419,14 +428,16 @@ dec_write_callback(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame,
                          sample_to_double(buffer[c][i], bps));
   }
 
-  value ret = caml_callback_exn(Dec_write(callbacks->callbacks), data);
+  ret = caml_callback_exn(Dec_write(callbacks->callbacks), data);
 
   if (Is_exception_result(ret)) {
     caml_remove_generational_global_root(&data);
+    caml_remove_generational_global_root(&ret);
     caml_raise(Extract_exception(ret));
   }
 
   caml_remove_generational_global_root(&data);
+  caml_remove_generational_global_root(&ret);
 
   caml_release_runtime_system();
 
@@ -674,20 +685,25 @@ enc_write_callback(const FLAC__StreamEncoder *encoder,
   ocaml_flac_register_thread();
   caml_acquire_runtime_system();
 
-  value buf = caml_alloc_string(bytes);
-
+  value buf = Val_unit;
+  value res = Val_unit;
   caml_register_generational_global_root(&buf);
+  caml_register_generational_global_root(&res);
+
+  buf = caml_alloc_string(bytes);
 
   memcpy(Bytes_val(buf), buffer, bytes);
 
-  value res = caml_callback_exn(Enc_write(callbacks), buf);
+  res = caml_callback_exn(Enc_write(callbacks), buf);
 
   if (Is_exception_result(res)) {
     caml_remove_generational_global_root(&buf);
+    caml_remove_generational_global_root(&res);
     caml_raise(Extract_exception(res));
   }
 
   caml_remove_generational_global_root(&buf);
+  caml_remove_generational_global_root(&res);
 
   caml_release_runtime_system();