diff --git a/epochX/cudacpp/CODEGEN/PLUGIN/CUDACPP_SA_OUTPUT/model_handling.py b/epochX/cudacpp/CODEGEN/PLUGIN/CUDACPP_SA_OUTPUT/model_handling.py
index 6e7a11d111..53213121d9 100644
--- a/epochX/cudacpp/CODEGEN/PLUGIN/CUDACPP_SA_OUTPUT/model_handling.py
+++ b/epochX/cudacpp/CODEGEN/PLUGIN/CUDACPP_SA_OUTPUT/model_handling.py
@@ -432,8 +432,8 @@ def define_expression(self):
                     else:
                         mydict['pre_%s' %c] = ''
                         mydict['post_%s'%c] = ''
-                # This affects '( *vertex ) = ' in HelAmps_sm.cc
-                out.write('    %(pre_vertex)svertex%(post_vertex)s = %(pre_coup)sCOUP%(post_coup)s * %(num)s;\n' % mydict)
+                # This affects '( *vertex ) = ' in HelAmps_sm.cc 
+                out.write('    %(pre_vertex)svertex%(post_vertex)s = Ccoeff * %(pre_coup)sCOUP%(post_coup)s * %(num)s;\n' % mydict)
             else:
                 mydict= {}
                 if self.type2def['pointer_vertex'] in ['*']:
@@ -464,6 +464,10 @@ def define_expression(self):
                 else:
                     mydict['declnamedenom'] = 'denom' # AV
                     self.declaration.add(('complex','denom'))
+                
+                # need to add the unary operator before the coupling                
+                if mydict['coup'] != 'one': # but in case where the coupling is not used (one)
+                    mydict['pre_coup'] = 'Ccoeff * %s' % mydict['pre_coup'] 
                 if not aloha.complex_mass:
                     # This affects 'denom = COUP' in HelAmps_sm.cc
                     if self.routine.denominator: