diff --git a/aioax25/frame.py b/aioax25/frame.py
index ad0711c..25ed3cc 100644
--- a/aioax25/frame.py
+++ b/aioax25/frame.py
@@ -1209,7 +1209,7 @@ class AX25SetAsyncBalancedModeFrame(AX25BaseUnnumberedFrame):
     AX.25 node.
     """
 
-    MODIFIER = 0b01101111
+    MODIFIER = 0b00101111
     CR = True
 
 
@@ -1224,7 +1224,7 @@ class AX25SetAsyncBalancedModeExtendedFrame(AX25BaseUnnumberedFrame):
     AX.25 node, using modulo 128 acknowledgements.
     """
 
-    MODIFIER = 0b00101111
+    MODIFIER = 0b01101111
     CR = True
 
 
diff --git a/tests/test_frame/test_uframe.py b/tests/test_frame/test_uframe.py
index 4faabe2..c0aaab3 100644
--- a/tests/test_frame/test_uframe.py
+++ b/tests/test_frame/test_uframe.py
@@ -42,7 +42,7 @@ def test_decode_sabm():
         from_hex(
             "ac 96 68 84 ae 92 e0"  # Destination
             "ac 96 68 9a a6 98 61"  # Source
-            "6f"  # Control byte
+            "2f"  # Control byte
         )
     )
     assert isinstance(
@@ -59,7 +59,7 @@ def test_decode_sabm_payload():
             from_hex(
                 "ac 96 68 84 ae 92 e0"  # Destination
                 "ac 96 68 9a a6 98 61"  # Source
-                "6f"  # Control byte
+                "2f"  # Control byte
                 "11 22 33 44 55"  # Payload
             )
         )