diff --git a/CHANGES b/CHANGES
index 2686cc4..2f6fd3b 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,8 @@
+0.5.1 (unreleased)
+=====
+* Use generational global roots to protect
+  encoder and decoder callbacks.
+
 0.5.0 (2023-09-05)
 =====
 * Cleanup API, get rid of global roots,
diff --git a/dune-project b/dune-project
index 0278b4f..7ee69b5 100644
--- a/dune-project
+++ b/dune-project
@@ -1,5 +1,5 @@
 (lang dune 2.8)
-(version 0.5.0)
+(version 0.5.1)
 (name flac)
 (source (github savonet/ocaml-flac))
 (license GPL-2.0-or-later)
diff --git a/src/flac_ogg_stubs.c b/src/flac_ogg_stubs.c
index 5a8b73e..2d4fa6f 100644
--- a/src/flac_ogg_stubs.c
+++ b/src/flac_ogg_stubs.c
@@ -69,7 +69,7 @@ CAMLprim value ocaml_flac_encoder_ogg_create(value comments, value params,
   ret = ocaml_flac_encoder_alloc(comments, params);
   ocaml_flac_encoder *enc = Encoder_val(ret);
 
-  enc->callbacks = _enc_cb;
+  caml_modify_generational_global_root(&enc->callbacks, _enc_cb);
 
   caml_release_runtime_system();
   FLAC__stream_encoder_set_ogg_serial_number(enc->encoder, serialno);
@@ -78,7 +78,7 @@ CAMLprim value ocaml_flac_encoder_ogg_create(value comments, value params,
                                        (void *)&enc->callbacks);
   caml_acquire_runtime_system();
 
-  enc->callbacks = Val_none;
+  caml_modify_generational_global_root(&enc->callbacks, Val_none);
 
   CAMLreturn(ret);
 }
diff --git a/src/flac_stubs.c b/src/flac_stubs.c
index fba0f4e..d780cc3 100644
--- a/src/flac_stubs.c
+++ b/src/flac_stubs.c
@@ -72,7 +72,7 @@ void ocaml_flac_register_thread() {
 /* Convenience functions */
 #ifdef BIGENDIAN
 static inline int16_t bswap_16(int16_t x) {
-  return ((((x) >> 8) & 0xff) | (((x)&0xff) << 8));
+  return ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8));
 }
 #endif
 
@@ -192,6 +192,8 @@ static void finalize_decoder(value e) {
     free(dec->callbacks.info);
   if (dec->callbacks.meta != NULL)
     FLAC__metadata_object_delete(dec->callbacks.meta);
+
+  caml_remove_generational_global_root(&dec->callbacks.callbacks);
   free(dec);
 }
 
@@ -441,10 +443,12 @@ value ocaml_flac_decoder_alloc() {
     caml_raise_out_of_memory();
 
   dec->decoder = FLAC__stream_decoder_new();
-  dec->callbacks.callbacks = NULL;
+  dec->callbacks.callbacks = Val_none;
   dec->callbacks.info = NULL;
   dec->callbacks.meta = NULL;
 
+  caml_register_generational_global_root(&dec->callbacks.callbacks);
+
   // Accept vorbis comments
   FLAC__stream_decoder_set_metadata_respond(dec->decoder,
                                             FLAC__METADATA_TYPE_VORBIS_COMMENT);
@@ -463,7 +467,7 @@ CAMLprim value ocaml_flac_decoder_create(value callbacks) {
   ans = ocaml_flac_decoder_alloc();
   ocaml_flac_decoder *dec = Decoder_val(ans);
 
-  dec->callbacks.callbacks = &callbacks;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, callbacks);
 
   // Intialize decoder
   caml_release_runtime_system();
@@ -473,7 +477,7 @@ CAMLprim value ocaml_flac_decoder_create(value callbacks) {
       dec_metadata_callback, dec_error_callback, (void *)&dec->callbacks);
   caml_acquire_runtime_system();
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   CAMLreturn(ans);
 }
@@ -482,14 +486,15 @@ CAMLprim value ocaml_flac_decoder_init(value d, value c) {
   CAMLparam2(d, c);
 
   ocaml_flac_decoder *dec = Decoder_val(d);
-  dec->callbacks.callbacks = &c;
+
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, c);
 
   // Process metadata
   caml_release_runtime_system();
   FLAC__stream_decoder_process_until_end_of_metadata(dec->decoder);
   caml_acquire_runtime_system();
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   CAMLreturn(Val_unit);
 }
@@ -498,11 +503,12 @@ CAMLprim value ocaml_flac_decoder_state(value d, value c) {
   CAMLparam2(d, c);
 
   ocaml_flac_decoder *dec = Decoder_val(d);
-  dec->callbacks.callbacks = &c;
+
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, c);
 
   int ret = FLAC__stream_decoder_get_state(dec->decoder);
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   CAMLreturn(val_of_state(ret));
 }
@@ -556,14 +562,15 @@ CAMLprim value ocaml_flac_decoder_process(value d, value c) {
   CAMLparam2(d, c);
 
   ocaml_flac_decoder *dec = Decoder_val(d);
-  dec->callbacks.callbacks = &c;
+
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, c);
 
   // Process one frame
   caml_release_runtime_system();
   FLAC__stream_decoder_process_single(dec->decoder);
   caml_acquire_runtime_system();
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   CAMLreturn(Val_unit);
 }
@@ -575,14 +582,15 @@ CAMLprim value ocaml_flac_decoder_seek(value d, value c, value pos) {
   FLAC_API FLAC__bool ret;
 
   ocaml_flac_decoder *dec = Decoder_val(d);
-  dec->callbacks.callbacks = &c;
+
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, c);
 
   // Process one frame
   caml_release_runtime_system();
   ret = FLAC__stream_decoder_seek_absolute(dec->decoder, offset);
   caml_acquire_runtime_system();
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   if (ret == true)
     CAMLreturn(Val_true);
@@ -596,14 +604,15 @@ CAMLprim value ocaml_flac_decoder_reset(value d, value c) {
   FLAC_API FLAC__bool ret;
 
   ocaml_flac_decoder *dec = Decoder_val(d);
-  dec->callbacks.callbacks = &c;
+
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, c);
 
   // Process one frame
   caml_release_runtime_system();
   ret = FLAC__stream_decoder_reset(dec->decoder);
   caml_acquire_runtime_system();
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   if (ret == true)
     CAMLreturn(Val_true);
@@ -617,14 +626,15 @@ CAMLprim value ocaml_flac_decoder_flush(value d, value c) {
   FLAC_API FLAC__bool ret;
 
   ocaml_flac_decoder *dec = Decoder_val(d);
-  dec->callbacks.callbacks = &c;
+
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, c);
 
   // Process one frame
   caml_release_runtime_system();
   ret = FLAC__stream_decoder_flush(dec->decoder);
   caml_acquire_runtime_system();
 
-  dec->callbacks.callbacks = NULL;
+  caml_modify_generational_global_root(&dec->callbacks.callbacks, Val_none);
 
   if (ret == true)
     CAMLreturn(Val_true);
@@ -644,6 +654,8 @@ static void finalize_encoder(value e) {
     free(enc->buf);
   if (enc->lines != NULL)
     free(enc->lines);
+
+  caml_remove_generational_global_root(&enc->callbacks);
   free(enc);
 }
 
@@ -763,6 +775,8 @@ value ocaml_flac_encoder_alloc(value comments, value params) {
   caml_enc->buf = NULL;
   caml_enc->lines = NULL;
 
+  caml_register_generational_global_root(&caml_enc->callbacks);
+
   // Fill custom value
   ret = caml_alloc_custom(&encoder_ops, sizeof(ocaml_flac_encoder *), 1, 0);
   Encoder_val(ret) = caml_enc;
@@ -802,7 +816,7 @@ CAMLprim value ocaml_flac_encoder_create(value comments, value params,
   ret = ocaml_flac_encoder_alloc(comments, params);
   ocaml_flac_encoder *enc = Encoder_val(ret);
 
-  enc->callbacks = callbacks;
+  caml_modify_generational_global_root(&enc->callbacks, callbacks);
 
   caml_release_runtime_system();
   FLAC__stream_encoder_init_stream(enc->encoder, enc_write_callback,
@@ -810,7 +824,7 @@ CAMLprim value ocaml_flac_encoder_create(value comments, value params,
                                    (void *)&enc->callbacks);
   caml_acquire_runtime_system();
 
-  enc->callbacks = Val_none;
+  caml_modify_generational_global_root(&enc->callbacks, Val_none);
 
   CAMLreturn(ret);
 }
@@ -865,14 +879,14 @@ CAMLprim value ocaml_flac_encoder_process(value _enc, value cb, value data,
           sample_from_double(Double_field(Field(data, c), i), Int_val(bps));
   }
 
-  enc->callbacks = cb;
+  caml_modify_generational_global_root(&enc->callbacks, cb);
 
   caml_release_runtime_system();
   FLAC__stream_encoder_process(enc->encoder,
                                (const FLAC__int32 *const *)enc->buf, samples);
   caml_acquire_runtime_system();
 
-  enc->callbacks = Val_none;
+  caml_modify_generational_global_root(&enc->callbacks, Val_none);
 
   CAMLreturn(Val_unit);
 }
@@ -882,13 +896,13 @@ CAMLprim value ocaml_flac_encoder_finish(value _enc, value c) {
 
   ocaml_flac_encoder *enc = Encoder_val(_enc);
 
-  enc->callbacks = c;
+  caml_modify_generational_global_root(&enc->callbacks, c);
 
   caml_release_runtime_system();
   FLAC__stream_encoder_finish(enc->encoder);
   caml_acquire_runtime_system();
 
-  enc->callbacks = Val_none;
+  caml_modify_generational_global_root(&enc->callbacks, Val_none);
 
   CAMLreturn(Val_unit);
 }
diff --git a/src/flac_stubs.h b/src/flac_stubs.h
index 7958e41..44eba5d 100644
--- a/src/flac_stubs.h
+++ b/src/flac_stubs.h
@@ -34,7 +34,7 @@ value flac_Val_some(value v);
 
 typedef struct ocaml_flac_decoder_callbacks {
   /* This is used for callback from caml. */
-  value *callbacks;
+  value callbacks;
   FLAC__StreamMetadata_StreamInfo *info;
   FLAC__StreamMetadata *meta;
 } ocaml_flac_decoder_callbacks;
@@ -44,12 +44,12 @@ typedef struct ocaml_flac_decoder {
   ocaml_flac_decoder_callbacks callbacks;
 } ocaml_flac_decoder;
 
-#define Dec_read(v) Field(*v, 0)
-#define Dec_seek(v) Field(*v, 1)
-#define Dec_tell(v) Field(*v, 2)
-#define Dec_length(v) Field(*v, 3)
-#define Dec_eof(v) Field(*v, 4)
-#define Dec_write(v) Field(*v, 5)
+#define Dec_read(v) Field(v, 0)
+#define Dec_seek(v) Field(v, 1)
+#define Dec_tell(v) Field(v, 2)
+#define Dec_length(v) Field(v, 3)
+#define Dec_eof(v) Field(v, 4)
+#define Dec_write(v) Field(v, 5)
 
 /* Caml abstract value containing the decoder. */
 #define Decoder_val(v) (*((ocaml_flac_decoder **)Data_custom_val(v)))