diff --git a/firmware/pico_rng_test.py b/firmware/pico_rng_test.py
index 42f241c..15963fb 100755
--- a/firmware/pico_rng_test.py
+++ b/firmware/pico_rng_test.py
@@ -12,6 +12,7 @@ import sys
 parser = argparse.ArgumentParser(description="Raspberry Pi Pico Random Number Generator Test Tool")
 parser.add_argument("--performance", action="store_true", help="Performance test the RNG.")
 parser.add_argument("--endless", action="store_true", help="Outputs random bytes endlessly.")
+parser.add_argument("--size", default="100", help="Number of bytes to output.")
 args = parser.parse_args()
 
 # If this is set, then the /dev/pico_rng file exists
@@ -42,24 +43,32 @@ start_time = (int(time.time()) - 1)
 def get_data():
     return rng_chardev.read(64) if rng_chardev else endpt.read(64, 500)
 
+def get_and_print():
+    data = get_data()
+    sys.stdout.buffer.write(data)
+
 if args.performance:
     while True:
         try:
             from_device = get_data()
             count = count+1
             #print(from_device, end="")
-            print("\t{0:.2f} KB/s".format((int((count * 64) / (int(time.time()) - start_time))) / 1024 ), end='\r')
+            print("Speed: {0:.2f} KB/s".format((int((count * 64) / (int(time.time()) - start_time))) / 1024 ), end='\r')
         except KeyboardInterrupt:
             exit(0)
 elif args.endless:
     while True:
         try:
-            data = get_data()
-            sys.stdout.buffer.write(data)
+            get_and_print()
         except KeyboardInterrupt:
             exit(0)
         except BrokenPipeError:
             exit(0)
+elif args.size:
+    size = int(float(args.size))
+    for i in range(0,size,64):
+        data = get_data()
+        sys.stdout.buffer.write(data[:min(size-i,len(data))])
 else:
     from_device = get_data()
     print(from_device)