diff --git a/components/gbc/gnuboy/src/loader.c b/components/gbc/gnuboy/src/loader.c
index 72e5238b..beb1cfdd 100644
--- a/components/gbc/gnuboy/src/loader.c
+++ b/components/gbc/gnuboy/src/loader.c
@@ -236,8 +236,17 @@ void rtc_load()
 void loader_unload()
 {
 	sram_save();
+	// Free the cart SRAM allocated in rom_load(). Previously this static buffer
+	// was never freed, leaking ~ramsize KB of PSRAM and fragmenting it across
+	// cart switches; it was also reused as-is on the next ROM via the
+	// `if (!sram_ptr)` guard, so a larger-ramsize cart would overflow it.
+	// Freeing (and NULLing) here makes each ROM reallocate at its own size.
+	if (sram_ptr) {
+		heap_caps_free(sram_ptr);
+		sram_ptr = NULL;
+	}
+	ram.sbank = NULL;
 	// rom.bank = NULL;
-	// ram.sbank = NULL;
 	mbc.type = mbc.romsize = mbc.ramsize = mbc.batt = 0;
 }
 
diff --git a/components/gbc/include/gbc_shared_memory.hpp b/components/gbc/include/gbc_shared_memory.hpp
index 41028dc2..c98c9491 100644
--- a/components/gbc/include/gbc_shared_memory.hpp
+++ b/components/gbc/include/gbc_shared_memory.hpp
@@ -3,6 +3,15 @@
 #include <cstdint>
 #include <cstddef>
 
+// Game Boy (Color) audio sizing. The shared PCM buffer allocation (in
+// gbc_shared_memory.cpp) and pcm.len (in gameboy.cpp) BOTH derive from these,
+// so they cannot diverge: if pcm.len implies a larger buffer than is allocated,
+// the gnuboy sound mixer overruns it and corrupts the heap.
+#define GAMEBOY_AUDIO_SAMPLE_RATE 32768
+// Size (in bytes) of the shared PCM buffer: ~1/5 second of stereo (2ch),
+// 16-bit (2 byte) audio. pcm.len = GBC_AUDIO_BUFFER_SIZE / sizeof(int16_t).
+#define GBC_AUDIO_BUFFER_SIZE (GAMEBOY_AUDIO_SAMPLE_RATE * 2 * 2 / 5)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/components/gbc/src/gameboy.cpp b/components/gbc/src/gameboy.cpp
index ce860d96..fe1c644d 100644
--- a/components/gbc/src/gameboy.cpp
+++ b/components/gbc/src/gameboy.cpp
@@ -11,7 +11,7 @@
 
 static const size_t GAMEBOY_SCREEN_WIDTH = 160;
 static const size_t GAMEBOY_SCREEN_HEIGHT = 144;
-static const int GAMEBOY_AUDIO_SAMPLE_RATE = 32768;
+// GAMEBOY_AUDIO_SAMPLE_RATE / GBC_AUDIO_BUFFER_SIZE come from gbc_shared_memory.hpp
 
 extern "C" {
 #include <gnuboy/loader.h>
@@ -116,7 +116,8 @@ void init_gameboy(const std::string& rom_filename, uint8_t *romdata, size_t rom_
   lcd->vbank = vram;
   ram.ibank = wram;
   pcm.buf = reinterpret_cast<int16_t*>(audio);
-  static constexpr int GBC_AUDIO_BUFFER_SIZE = GAMEBOY_AUDIO_SAMPLE_RATE * 2 * 2 / 5; // TODO: 5 is a hack to make it work
+  // GBC_AUDIO_BUFFER_SIZE (bytes) is the size actually allocated for pcm.buf in
+  // gbc_shared_memory.cpp, so pcm.len matches the buffer exactly.
   pcm.len = GBC_AUDIO_BUFFER_SIZE / sizeof(int16_t);
 
   // set native size
diff --git a/components/gbc/src/gbc_shared_memory.cpp b/components/gbc/src/gbc_shared_memory.cpp
index 369a3ca3..d365a5b2 100644
--- a/components/gbc/src/gbc_shared_memory.cpp
+++ b/components/gbc/src/gbc_shared_memory.cpp
@@ -22,7 +22,8 @@ extern "C" {
 // GBC memory sizes
 #define GBC_VRAM_SIZE (16 * 1024)  // 16KB VRAM
 #define GBC_WRAM_SIZE (32 * 1024)  // 32KB WRAM
-#define GBC_AUDIO_BUFFER_SIZE (2048 * sizeof(int16_t))  // 2048 samples at 16-bit per sample
+// GBC_AUDIO_BUFFER_SIZE comes from gbc_shared_memory.hpp so the allocation here
+// always matches pcm.len in gameboy.cpp (a mismatch overruns the PCM buffer).
 
 // Static pointers to shared memory regions
 static uint8_t* vram_ptr = nullptr;