diff --git a/src/ctobssim/ctobssim.cpp b/src/ctobssim/ctobssim.cpp
index e40a25d..5ca3814 100644
--- a/src/ctobssim/ctobssim.cpp
+++ b/src/ctobssim/ctobssim.cpp
@@ -570,6 +570,11 @@ void ctobssim::get_parameters(void)
         m_obs = get_observations();
     }
 
+    // ... otherwise make sure that observation boundaries are set
+    else {
+        set_obs_bounds(m_obs);
+    }
+
     // Read model definition file if required
     if (m_obs.models().size() == 0) {
        std::string inmodel = (*this)["inmodel"].filename();
diff --git a/src/support/ctool.cpp b/src/support/ctool.cpp
index 6e9e38b..b067e97 100644
--- a/src/support/ctool.cpp
+++ b/src/support/ctool.cpp
@@ -869,8 +869,6 @@ void ctool::set_obs_bounds(GObservations& obs)
 }
 
 
-
-
 /***********************************************************************//**
  * @brief Derives mean pointing from CTA observations
  *