diff --git a/minimp3.h b/minimp3.h
index 3220ae1..5e3f4f1 100644
--- a/minimp3.h
+++ b/minimp3.h
@@ -15,12 +15,8 @@ typedef struct
     int frame_bytes, frame_offset, channels, hz, layer, bitrate_kbps;
 } mp3dec_frame_info_t;
 
-typedef struct
-{
-    float mdct_overlap[2][9*32], qmf_state[15*2*32];
-    int reserv, free_format_bytes;
-    unsigned char header[4], reserv_buf[511];
-} mp3dec_t;
+struct mp3dec_s;
+typedef struct mp3dec_s mp3dec_t;
 
 #ifdef __cplusplus
 extern "C" {
@@ -238,6 +234,19 @@ typedef struct
     uint8_t ist_pos[2][39];
 } mp3dec_scratch_t;
 
+struct mp3dec_s
+{
+    float mdct_overlap[2][9*32], qmf_state[15*2*32];
+    int reserv, free_format_bytes;
+    unsigned char header[4], reserv_buf[511];
+
+    mp3dec_scratch_t scratch;
+
+#if !defined(MINIMP3_ONLY_MP3)
+        L12_scale_info sci[1];
+#endif
+};
+
 static void bs_init(bs_t *bs, const uint8_t *data, int bytes)
 {
     bs->buf   = data;
@@ -1715,7 +1724,6 @@ int mp3dec_decode_frame(mp3dec_t *dec, const uint8_t *mp3, int mp3_bytes, mp3d_s
     int i = 0, igr, frame_size = 0, success = 1;
     const uint8_t *hdr;
     bs_t bs_frame[1];
-    mp3dec_scratch_t scratch;
 
     if (mp3_bytes > 4 && dec->header[0] == 0xff && hdr_compare(dec->header, mp3))
     {
@@ -1758,40 +1766,39 @@ int mp3dec_decode_frame(mp3dec_t *dec, const uint8_t *mp3, int mp3_bytes, mp3d_s
 
     if (info->layer == 3)
     {
-        int main_data_begin = L3_read_side_info(bs_frame, scratch.gr_info, hdr);
+        int main_data_begin = L3_read_side_info(bs_frame, dec->scratch.gr_info, hdr);
         if (main_data_begin < 0 || bs_frame->pos > bs_frame->limit)
         {
             mp3dec_init(dec);
             return 0;
         }
-        success = L3_restore_reservoir(dec, bs_frame, &scratch, main_data_begin);
+        success = L3_restore_reservoir(dec, bs_frame, &dec->scratch, main_data_begin);
         if (success)
         {
             for (igr = 0; igr < (HDR_TEST_MPEG1(hdr) ? 2 : 1); igr++, pcm += 576*info->channels)
             {
-                memset(scratch.grbuf[0], 0, 576*2*sizeof(float));
-                L3_decode(dec, &scratch, scratch.gr_info + igr*info->channels, info->channels);
-                mp3d_synth_granule(dec->qmf_state, scratch.grbuf[0], 18, info->channels, pcm, scratch.syn[0]);
+                memset(dec->scratch.grbuf[0], 0, 576*2*sizeof(float));
+                L3_decode(dec, &dec->scratch, dec->scratch.gr_info + igr*info->channels, info->channels);
+                mp3d_synth_granule(dec->qmf_state, dec->scratch.grbuf[0], 18, info->channels, pcm, dec->scratch.syn[0]);
             }
         }
-        L3_save_reservoir(dec, &scratch);
+        L3_save_reservoir(dec, &dec->scratch);
     } else
     {
 #ifdef MINIMP3_ONLY_MP3
         return 0;
 #else /* MINIMP3_ONLY_MP3 */
-        L12_scale_info sci[1];
-        L12_read_scale_info(hdr, bs_frame, sci);
+        L12_read_scale_info(hdr, bs_frame, dec->sci);
 
-        memset(scratch.grbuf[0], 0, 576*2*sizeof(float));
+        memset(dec->scratch.grbuf[0], 0, 576*2*sizeof(float));
         for (i = 0, igr = 0; igr < 3; igr++)
         {
-            if (12 == (i += L12_dequantize_granule(scratch.grbuf[0] + i, bs_frame, sci, info->layer | 1)))
+            if (12 == (i += L12_dequantize_granule(dec->scratch.grbuf[0] + i, bs_frame, dec->sci, info->layer | 1)))
             {
                 i = 0;
-                L12_apply_scf_384(sci, sci->scf + igr, scratch.grbuf[0]);
-                mp3d_synth_granule(dec->qmf_state, scratch.grbuf[0], 12, info->channels, pcm, scratch.syn[0]);
-                memset(scratch.grbuf[0], 0, 576*2*sizeof(float));
+                L12_apply_scf_384(dec->sci, dec->sci->scf + igr, dec->scratch.grbuf[0]);
+                mp3d_synth_granule(dec->qmf_state, dec->scratch.grbuf[0], 12, info->channels, pcm, dec->scratch.syn[0]);
+                memset(dec->scratch.grbuf[0], 0, 576*2*sizeof(float));
                 pcm += 384*info->channels;
             }
             if (bs_frame->pos > bs_frame->limit)