diff --git a/arm9/src/storage.c b/arm9/src/storage.c
index abcd219..4fdd564 100644
--- a/arm9/src/storage.c
+++ b/arm9/src/storage.c
@@ -384,7 +384,7 @@ bool deleteDir(char const* path)
 	return result;
 }
 
-unsigned long long getDirSize(const char* path)
+unsigned long long getDirSize(const char* path, u32 blockSize)
 {
 	if (!path) return 0;
 
@@ -404,7 +404,7 @@ unsigned long long getDirSize(const char* path)
 				char fullpath[512];
 				sprintf(fullpath, "%s/%s", path, ent->d_name);
 
-				size += getDirSize(fullpath);
+				size += getDirSize(fullpath, blockSize);
 			}
 			else
 			{				
@@ -412,6 +412,10 @@ unsigned long long getDirSize(const char* path)
 				sprintf(fullpath, "%s/%s", path, ent->d_name);				
 
 				size += getFileSizePath(fullpath);
+
+				// If we've specified a block size, round up to it
+				if ((size % blockSize) != 0)
+					size += blockSize - (size % blockSize);
 			}
 		}
 	}
@@ -493,7 +497,7 @@ unsigned long long getSDCardFree()
 	if (sdIsInserted())
 	{
 		struct statvfs st;
-		if (statvfs("/", &st) == 0)
+		if (statvfs("sd:/", &st) == 0)
 			return st.f_bsize * st.f_bavail;
 	}
 
@@ -503,18 +507,31 @@ unsigned long long getSDCardFree()
 //internal storage
 unsigned long long getDsiSize()
 {
-	struct statvfs st;
-	if (statvfs("nand:/", &st) == 0)
-		return st.f_bsize * st.f_blocks;
-
-	return 0;
+	//The DSi has 256MB of internal storage. Some is unavailable and used by other things.
+	//An empty DSi reads 1024 open blocks
+	return 1024 * BYTES_PER_BLOCK;
 }
 
 unsigned long long getDsiFree()
 {
+	u32 blockSize = 0;
 	struct statvfs st;
 	if (statvfs("nand:/", &st) == 0)
-		return st.f_bsize * st.f_bavail;
+		blockSize = st.f_bsize;
 
-	return 0;
+	//Get free space by subtracting file sizes in nand folders
+	unsigned long long size = getDsiSize();
+	unsigned long long appSize = getDirSize(sdnandMode ? "sd:/title/00030004" : "nand:/title/00030004", blockSize);
+
+	//subtract, but don't go under 0
+	if (appSize > size)
+	{
+		size = 0;
+	}
+	else
+	{
+		size -= appSize;
+	}
+
+	return size;
 }
\ No newline at end of file
diff --git a/arm9/src/storage.h b/arm9/src/storage.h
index 18ce0f1..8701cf6 100644
--- a/arm9/src/storage.h
+++ b/arm9/src/storage.h
@@ -26,7 +26,7 @@ bool padFile(char const* path, int size);
 bool dirExists(char const* path);
 bool copyDir(char const* src, char const* dst);
 bool deleteDir(char const* path);
-unsigned long long getDirSize(char const* path);
+unsigned long long getDirSize(char const* path, u32 blockSize);
 
 //home menu
 int getMenuSlots();
diff --git a/arm9/src/testmenu.c b/arm9/src/testmenu.c
index 1b8548b..4e16114 100644
--- a/arm9/src/testmenu.c
+++ b/arm9/src/testmenu.c
@@ -61,7 +61,7 @@ void testMenu()
 		iprintf("\n");
 		swiWaitForVBlank();
 
-		printf("\t%.0f / %.0f blocks\n", (float)free / BYTES_PER_BLOCK, (float)size / BYTES_PER_BLOCK);
+		iprintf("\t%d / %d blocks\n", free / BYTES_PER_BLOCK, size / BYTES_PER_BLOCK);
 	}
 
 	//end
diff --git a/arm9/src/titlemenu.c b/arm9/src/titlemenu.c
index 5ae2433..9b9211d 100644
--- a/arm9/src/titlemenu.c
+++ b/arm9/src/titlemenu.c
@@ -278,9 +278,9 @@ static void backup(Menu* m)
 		char* srcpath = (char*)malloc(strlen("nand:/title/") + 32);
 		sprintf(srcpath, "%s:/title/%08x/%08x", sdnandMode ? "sd" : "nand", (unsigned int)tid_high, (unsigned int)tid_low);
 
-		if (getSDCardFree() < getDirSize(srcpath))
+		if (getSDCardFree() < getDirSize(srcpath, 0))
 		{
-			messageBox("Not enough space on NAND.");
+			messageBox("Not enough space on SD.");
 		}
 		else
 		{