diff --git a/cscripts/csobsinfo.py b/cscripts/csobsinfo.py
index 10ef2cc..30a0b32 100755
--- a/cscripts/csobsinfo.py
+++ b/cscripts/csobsinfo.py
@@ -52,7 +52,7 @@ class csobsinfo(ctools.cscript):
         self._gti            = gammalib.GGti()
 
         # Initialise observation container from constructor arguments.
-        self._obs = self._set_input_obs(argv)
+        self._obs, argv = self._set_input_obs(argv)
 
         # Initialise application by calling the appropriate class
         # constructor.
diff --git a/cscripts/cspull.py b/cscripts/cspull.py
index 25f68a9..0f1e47d 100755
--- a/cscripts/cspull.py
+++ b/cscripts/cspull.py
@@ -62,7 +62,7 @@ class cspull(ctools.cscript):
         self._log_clients = False
 
         # Initialise observation container from constructor arguments.
-        self._obs = self._set_input_obs(argv)
+        self._obs, argv = self._set_input_obs(argv)
 
         # Initialise application by calling the appropriate class
         # constructor.
diff --git a/cscripts/csresmap.py b/cscripts/csresmap.py
index 8559c87..4197d23 100755
--- a/cscripts/csresmap.py
+++ b/cscripts/csresmap.py
@@ -74,7 +74,7 @@ class csresmap(ctools.cscript):
         self._log_clients  = False
 
         # Initialise observation container from constructor arguments.
-        self._obs = self._set_input_obs(argv)
+        self._obs, argv = self._set_input_obs(argv)
 
         # Initialise application by calling the appropriate class
         # constructor.
diff --git a/cscripts/csspec.py b/cscripts/csspec.py
index 6ef8762..dc4d131 100755
--- a/cscripts/csspec.py
+++ b/cscripts/csspec.py
@@ -60,7 +60,7 @@ class csspec(ctools.cscript):
         self._debug       = False
 
         # Initialise observation container from constructor arguments.
-        self._obs = self._set_input_obs(argv)
+        self._obs, argv = self._set_input_obs(argv)
 
         # Initialise application by calling the appropriate class
         # constructor.