diff --git a/external/tremor/os_types.h b/external/tremor/os_types.h
index 8d444d6..857f340 100644
--- a/external/tremor/os_types.h
+++ b/external/tremor/os_types.h
@@ -27,10 +27,19 @@
 
 /* make it easy on the folks that want to compile the libs with a
    different malloc than stdlib */
+#ifdef ESP_PLATFORM
+/* decoder state and codebooks in PSRAM: keeps internal RAM free */
+#include "esp_heap_caps.h"
+#define _ogg_malloc(s)     heap_caps_malloc((s), MALLOC_CAP_SPIRAM)
+#define _ogg_calloc(n, s)  heap_caps_calloc((n), (s), MALLOC_CAP_SPIRAM)
+#define _ogg_realloc(p, s) heap_caps_realloc((p), (s), MALLOC_CAP_SPIRAM)
+#define _ogg_free          free
+#else
 #define _ogg_malloc  malloc
 #define _ogg_calloc  calloc
 #define _ogg_realloc realloc
 #define _ogg_free    free
+#endif
 
 #ifdef _WIN32