diff --git a/bumble/rfcomm.py b/bumble/rfcomm.py
index 18eea06..fba2e0f 100644
--- a/bumble/rfcomm.py
+++ b/bumble/rfcomm.py
@@ -671,15 +671,17 @@ class DLC(utils.EventEmitter):
     def process_tx(self) -> None:
         # Send anything we can (or an empty frame if we need to send rx credits)
         rx_credits_needed = self.rx_credits_needed()
-        while (self.tx_buffer and self.tx_credits > 0) or (
-            rx_credits_needed > 0 and self.tx_credit > 0
-        ):
+        while (self.tx_buffer and self.tx_credits > 0) or rx_credits_needed > 0:
             # Get the next chunk, up to MTU size
             if rx_credits_needed > 0:
-                chunk = bytes([rx_credits_needed]) + self.tx_buffer[: self.mtu - 1]
-                self.tx_buffer = self.tx_buffer[len(chunk) - 1 :]
+                chunk = bytes([rx_credits_needed])
                 self.rx_credits += rx_credits_needed
-                tx_credit_spent = len(chunk) > 1
+                if self.tx_buffer and self.tx_credits > 0:
+                    chunk += self.tx_buffer[: self.mtu - 1]
+                    self.tx_buffer = self.tx_buffer[len(chunk) - 1 :]
+                    tx_credit_spent = True
+                else:
+                    tx_credit_spent = False
             else:
                 chunk = self.tx_buffer[: self.mtu]
                 self.tx_buffer = self.tx_buffer[len(chunk) :]