diff --git a/tb/test_axis_cobs_decode.py b/tb/test_axis_cobs_decode.py
index 53540002..fe4c5b48 100755
--- a/tb/test_axis_cobs_decode.py
+++ b/tb/test_axis_cobs_decode.py
@@ -90,9 +90,8 @@ def cobs_decode(block):
         i += 1
         if i+code-1 > len(block):
             return None
-        for k in range(code-1):
-            dec.append(block[i])
-            i += 1
+        dec.extend(block[i:i+code-1])
+        i += code-1
         if code < 255 and i < len(block):
             dec.append(0)
 
diff --git a/tb/test_axis_cobs_encode.py b/tb/test_axis_cobs_encode.py
index ca376cab..f3892f89 100755
--- a/tb/test_axis_cobs_encode.py
+++ b/tb/test_axis_cobs_encode.py
@@ -91,9 +91,8 @@ def cobs_decode(block):
         i += 1
         if i+code-1 > len(block):
             return None
-        for k in range(code-1):
-            dec.append(block[i])
-            i += 1
+        dec.extend(block[i:i+code-1])
+        i += code-1
         if code < 255 and i < len(block):
             dec.append(0)