diff --git a/libpsx/src/spu.c b/libpsx/src/spu.c
index 53ddf2d..e46d153 100644
--- a/libpsx/src/spu.c
+++ b/libpsx/src/spu.c
@@ -164,6 +164,8 @@ void SsUpload(const void *addr, int size, int spu_addr)
 
 	while(size > 0)
 	{
+		int n = size / sizeof *ptr > 32 ? 32 : size / sizeof *ptr;
+
 		SPU_STATUS = 4; // Sound RAM Data Transfer Control
 		SPU_CONTROL = SPU_CONTROL & ~0x30; // SPUCNT.transfer_mode = 0 (STOP)
 
@@ -173,7 +175,7 @@ void SsUpload(const void *addr, int size, int spu_addr)
 
 		SPU_ADDR = spu_addr >> 3;
 
-		for(i = 0; i < 32; i++)
+		for(i = 0; i < n; i++)
 			SPU_DATA = ptr[i];
 
 		SPU_CONTROL = (SPU_CONTROL & ~0x30) | 16; // SPUCNT.transfer_mode = 1 (MANUAL)
@@ -183,9 +185,9 @@ void SsUpload(const void *addr, int size, int spu_addr)
 
 		while(SPU_STATUS2 & 0x400); // wait for transfer busy bit to be cleared
 
-		spu_addr += 64;
-		ptr += 32;
-		size-=64;
+		spu_addr += n * sizeof *ptr;
+		ptr += n;
+		size-=n * sizeof *ptr;
 	}
 }