diff --git a/cscripts/csmodelmerge.py b/cscripts/csmodelmerge.py
index ff67612..1a15a72 100755
--- a/cscripts/csmodelmerge.py
+++ b/cscripts/csmodelmerge.py
@@ -121,7 +121,7 @@ class csmodelmerge(ctools.cscript):
             msg = "Parameter \"inmodels\" must contain either an @ASCII"+\
                   " file, a comma-separated or whitespace-separated list"+\
                   " of files or a wildcard string"
-            raise gammalib.GException.invalid_argument("csmodelmerge::get_parameters", msg) 
+            raise RuntimeError(msg) 
         
         # Get output file
         self.outmodel = self["outmodel"].filename()
diff --git a/cscripts/csobsdef.py b/cscripts/csobsdef.py
index 0c54f02..0b4a4aa 100755
--- a/cscripts/csobsdef.py
+++ b/cscripts/csobsdef.py
@@ -249,8 +249,7 @@ class csobsdef(ctools.cscript):
                 pntdir = gammalib.GSkyDir()
                 pntdir.lb_deg(lon,lat)
             else:
-                raise gammalib.GException.invalid_value(self.name,
-                      "No (ra,dec) or (lon,lat) columns found in pointing"
+                raise RuntimeError("No (ra,dec) or (lon,lat) columns found in pointing"
                       " definition file.")
             obs.pointing(gammalib.GCTAPointing(pntdir))
 
diff --git a/cscripts/cssens.py b/cscripts/cssens.py
index 64f34a7..a0a12ae 100755
--- a/cscripts/cssens.py
+++ b/cscripts/cssens.py
@@ -241,7 +241,7 @@ class cssens(ctools.cscript):
             else:
                 msg = "Invalid sensitivity type \""+self.m_type+"\" encountered."+ \
                       " Either use \"Differential\" or \"Integral\"."
-                raise gammalib.GException.invalid_value("cssens", msg)
+                raise RuntimeError(msg)
 
             # Determine sensitivity
             result = self.get_sensitivity(self.obs, emin, emax,
@@ -347,7 +347,7 @@ class cssens(ctools.cscript):
         if not model.has_par("Prefactor"):
             msg = "Model \""+self.m_srcname+"\" has no parameter \"Prefactor\"."+ \
                   " Only spectral models with a \"Prefactor\" parameter are supported."
-            raise gammalib.GException.invalid_value("cssens", msg)
+            raise RuntimeError(msg)
 
         # Set source position
         if self.m_ra != None and self.m_dec != None:
diff --git a/cscripts/csspec.py b/cscripts/csspec.py
index 54a6349..bbe80a0 100755
--- a/cscripts/csspec.py
+++ b/cscripts/csspec.py
@@ -206,7 +206,7 @@ class csspec(ctools.cscript):
                       "cube does not overlap with specified energy range ["+ \
                       str(emin)+", "+str(emax)+"]. Specify "+ \
                       "overlapping energy range."
-                raise gammalib.GException.invalid_argument("csspec", msg)
+                raise RuntimeError(msg)
 
             # Determine number of layers to use for each spectral bin
             n_layers = int(len(use_layers) / self.m_enumbins)
diff --git a/cscripts/cstsdist.py b/cscripts/cstsdist.py
index 282d2c8..c4b2b49 100755
--- a/cscripts/cstsdist.py
+++ b/cscripts/cstsdist.py
@@ -275,7 +275,7 @@ class cstsdist(ctools.cscript):
         if not model.has_par("Prefactor"):
             msg = "Model \""+self.m_srcname+"\" has no parameter \"Prefactor\"."+ \
                   " Only spectral models with a \"Prefactor\" parameter are supported."
-            raise gammalib.GException.invalid_value("cssens", msg)
+            raise RuntimeError(msg)
 
         # Fit or fix spatial parameters
         if fitpos:
diff --git a/cscripts/cstsmapmerge.py b/cscripts/cstsmapmerge.py
index df444d9..5ab465e 100755
--- a/cscripts/cstsmapmerge.py
+++ b/cscripts/cstsmapmerge.py
@@ -123,13 +123,13 @@ class cstsmapmerge(ctools.cscript):
             msg = "Parameter \"inmmaps\" must contain either an @ASCII file,"+\
                   " a comma-separated or whitespace-separated list of files"+\
                   " or a wildcard string"
-            raise gammalib.GException.invalid_argument("cstsmapmerge::get_parameters", msg) 
+            raise RuntimeError(msg) 
 
         # Check number of files. We need at least two files.
         if len(self.files) <= 1:
             msg = "Need at least two files to start merging, "+\
                   str(len(self.files))+" files given."
-            raise gammalib.GException.invalid_argument("cstsmapmerge::get_parameters", msg) 
+            raise RuntimeError(msg) 
         
         # Get output file
         self.outmap = self["outmap"].filename()
@@ -217,7 +217,7 @@ class cstsmapmerge(ctools.cscript):
                           " been merged. File \""+fitsfile+"\" contains"+\
                           " already merged bins. Set hidden parameter"+\
                           " overwrite=yes to avoid this error."
-                    raise gammalib.GException.invalid_value("cstsmapmerge::add", msg)
+                    raise RuntimeError(msg)
                 
                 # Copy TS values
                 self.tsmap[i] = add_tsmap[i]