diff --git a/py25/bacpypes/appservice.py b/py25/bacpypes/appservice.py
index b30a7e8..b411c02 100755
--- a/py25/bacpypes/appservice.py
+++ b/py25/bacpypes/appservice.py
@@ -1525,7 +1525,7 @@ class ApplicationServiceAccessPoint(ApplicationServiceElement, ServiceAccessPoin
                 xpdu = atype()
                 xpdu.decode(apdu)
             except Exception, err:
-                ApplicationServiceAccessPoint._exception("unconfirmed request decoding error: %r", err)
+                ApplicationServiceAccessPoint._exception("complex ack decoding error: %r", err)
                 return
 
         elif isinstance(apdu, ErrorPDU):
diff --git a/py27/bacpypes/appservice.py b/py27/bacpypes/appservice.py
index 641e655..7adace6 100755
--- a/py27/bacpypes/appservice.py
+++ b/py27/bacpypes/appservice.py
@@ -1522,7 +1522,7 @@ class ApplicationServiceAccessPoint(ApplicationServiceElement, ServiceAccessPoin
                 xpdu = atype()
                 xpdu.decode(apdu)
             except Exception as err:
-                ApplicationServiceAccessPoint._exception("unconfirmed request decoding error: %r", err)
+                ApplicationServiceAccessPoint._exception("complex ack decoding error: %r", err)
                 return
 
         elif isinstance(apdu, ErrorPDU):
diff --git a/py34/bacpypes/appservice.py b/py34/bacpypes/appservice.py
index 43316f1..75591f7 100755
--- a/py34/bacpypes/appservice.py
+++ b/py34/bacpypes/appservice.py
@@ -1522,7 +1522,7 @@ class ApplicationServiceAccessPoint(ApplicationServiceElement, ServiceAccessPoin
                 xpdu = atype()
                 xpdu.decode(apdu)
             except Exception as err:
-                ApplicationServiceAccessPoint._exception("unconfirmed request decoding error: %r", err)
+                ApplicationServiceAccessPoint._exception("complex ack decoding error: %r", err)
                 return
 
         elif isinstance(apdu, ErrorPDU):