diff --git a/inst/cta/src/GCTACubeBackground.cpp b/inst/cta/src/GCTACubeBackground.cpp
index 78da8fa..42f0fb3 100644
--- a/inst/cta/src/GCTACubeBackground.cpp
+++ b/inst/cta/src/GCTACubeBackground.cpp
@@ -45,6 +45,7 @@
 /* __ Method name definitions ____________________________________________ */
 #define G_READ                             "GCTACubeBackground::read(GFits&)"
 #define G_MC                "GCTACubeBackground::mc(GEnergy&, GTime&, GRan&)"
+#define G_FILL              "GCTACubeBackground::fill(GObservations&, GLog*)"
 
 /* __ Macros _____________________________________________________________ */
 
@@ -326,6 +327,14 @@ void GCTACubeBackground::fill(const GObservations& obs, GLog* log)
         // Extract region of interest from CTA observation
         GCTARoi roi = cta->roi();
 
+        // Check for RoI sanity
+        if (!roi.is_valid()) {
+            std::string msg = "No RoI information found in input observation "
+                              "\""+cta->name()+"\". Run ctselect to specify "
+                              "an RoI for this observation";
+            throw GException::invalid_value(G_FILL, msg);
+        }
+
         // Set GTI of actual observations as the GTI of the event cube
         eventcube.gti(cta->gti());
 
diff --git a/inst/cta/src/GCTACubeExposure.cpp b/inst/cta/src/GCTACubeExposure.cpp
index be2aeeb..a7b4d00 100644
--- a/inst/cta/src/GCTACubeExposure.cpp
+++ b/inst/cta/src/GCTACubeExposure.cpp
@@ -37,6 +37,8 @@
 #include "GLog.hpp"
 
 /* __ Method name definitions ____________________________________________ */
+#define G_SET                       "GCTACubeExposure::set(GCTAObservation&)"
+#define G_FILL                "GCTACubeExposure::fill(GObservations&, GLog*)"
 
 /* __ Macros _____________________________________________________________ */
 
@@ -311,6 +313,14 @@ void GCTACubeExposure::set(const GCTAObservation& obs)
         // Extract region of interest from CTA observation
         GCTARoi roi = obs.roi();
 
+        // Check for RoI sanity
+        if (!roi.is_valid()) {
+            std::string msg = "No RoI information found in input observation "
+                              "\""+obs.name()+"\". Run ctselect to specify "
+                              "an RoI for this observation";
+            throw GException::invalid_value(G_SET, msg);
+        }
+
         // Get references on CTA response and pointing direction
         const GCTAResponseIrf* rsp = dynamic_cast<const GCTAResponseIrf*>(obs.response());
         const GSkyDir&         pnt = obs.pointing().dir();
@@ -413,6 +423,14 @@ void GCTACubeExposure::fill(const GObservations& obs, GLog* log)
         // Extract region of interest from CTA observation
         GCTARoi roi = cta->roi();
 
+        // Check for RoI sanity
+        if (!roi.is_valid()) {
+            std::string msg = "No RoI information found in input observation "
+                              "\""+cta->name()+"\". Run ctselect to specify "
+                              "an RoI for this observation";
+            throw GException::invalid_value(G_FILL, msg);
+        }
+
         // Get references on CTA response and pointing direction
         const GCTAResponseIrf* rsp = dynamic_cast<const GCTAResponseIrf*>(cta->response());
         const GSkyDir&         pnt = cta->pointing().dir();
diff --git a/inst/cta/src/GCTACubePsf.cpp b/inst/cta/src/GCTACubePsf.cpp
index 4804195..3946915 100644
--- a/inst/cta/src/GCTACubePsf.cpp
+++ b/inst/cta/src/GCTACubePsf.cpp
@@ -38,6 +38,7 @@
 
 /* __ Method name definitions ____________________________________________ */
 #define G_SET                            "GCTACubePsf::set(GCTAObservation&)"
+#define G_FILL                     "GCTACubePsf::fill(GObservations&, GLog*)"
 
 /* __ Macros _____________________________________________________________ */
 
@@ -372,6 +373,14 @@ void GCTACubePsf::set(const GCTAObservation& obs)
         }
         const GCTARoi& roi = list->roi();
 
+        // Check for RoI sanity
+        if (!roi.is_valid()) {
+            std::string msg = "No RoI information found in input observation "
+                              "\""+obs.name()+"\". Run ctselect to specify "
+                              "an RoI for this observation";
+            throw GException::invalid_value(G_SET, msg);
+        }
+
         // Get references on CTA response and pointing direction
         const GCTAResponseIrf* rsp = dynamic_cast<const GCTAResponseIrf*>(obs.response());
         const GSkyDir&         pnt = obs.pointing().dir();
@@ -478,6 +487,14 @@ void GCTACubePsf::fill(const GObservations& obs, GLog* log)
         // Extract region of interest from CTA observation
         GCTARoi roi = cta->roi();
 
+        // Check for RoI sanity
+        if (!roi.is_valid()) {
+            std::string msg = "No RoI information found in input observation "
+                              "\""+cta->name()+"\". Run ctselect to specify "
+                              "an RoI for this observation";
+            throw GException::invalid_value(G_FILL, msg);
+        }
+
         // Get references on CTA response and pointing direction
         const GCTAResponseIrf* rsp = dynamic_cast<const GCTAResponseIrf*>(cta->response());
         const GSkyDir&         pnt = cta->pointing().dir();