diff --git a/openhtf/plugs/usb/adb_protocol.py b/openhtf/plugs/usb/adb_protocol.py
index 8982acfa5..7d85b4e1b 100644
--- a/openhtf/plugs/usb/adb_protocol.py
+++ b/openhtf/plugs/usb/adb_protocol.py
@@ -424,7 +424,7 @@ def IsOpen(self):
     return self.closed_state == self.ClosedState.OPEN
 
   def IsClosed(self):
-    """Return true ifff the transport layer is closed."""
+    """Return true iff the transport layer is closed."""
     return self.closed_state == self.ClosedState.CLOSED
 
   def EnqueueMessage(self, message, timeout):