diff --git a/src/ctobssim/ctobssim.cpp b/src/ctobssim/ctobssim.cpp
index 5a8d318..3d9c721 100644
--- a/src/ctobssim/ctobssim.cpp
+++ b/src/ctobssim/ctobssim.cpp
@@ -33,6 +33,7 @@
 #include "GTools.hpp"
 
 /* __ Method name definitions ____________________________________________ */
+#define G_GET_PARAMETERS                         "ctobssim::get_parameters()"
 #define G_SIMULATE_SOURCE      "ctobssim::simulate_source(GCTAObservation*, "\
                                                     "GModels&, GRan&, GLog*)"
 
@@ -577,7 +578,13 @@ void ctobssim::get_parameters(void)
     // If there are no observations in container then load them via user
     // parameters
     if (m_obs.size() == 0) {
+
+        // Throw exception if counts cube is given
+        require_inobs_nocube(G_GET_PARAMETERS);
+
+        // Get observation container
         m_obs = get_observations();
+        
     }
 
     // ... otherwise make sure that observation boundaries are set