diff --git a/arb.h b/arb.h
index d772915..c797d5c 100644
--- a/arb.h
+++ b/arb.h
@@ -3,7 +3,7 @@
 #include <atomic>
 #include "logcat_thread.h"
 
-#define ARB_MAX_SIZE 16
+#define ARB_MAX_SIZE 255
 
 template<typename T>
 class AtomicRingBuffer {
@@ -15,7 +15,7 @@ public:
 private:
     size_t _read = 0;
     size_t _write = 0;
-    std::atomic<char> _used = 0;
+    std::atomic<unsigned char> _used = 0;
     T _items[ARB_MAX_SIZE];
 };