diff --git a/src/proc/control/command-registry.hpp b/src/proc/control/command-registry.hpp
index 956a732bd..5631a3120 100644
--- a/src/proc/control/command-registry.hpp
+++ b/src/proc/control/command-registry.hpp
@@ -103,7 +103,8 @@ namespace control {
       bool
       operator() (const Command *pC1, const Command *pC2)  const
         {
-          return ( pC1 &&  pC2  && (*pC1 < *pC2));
+          return (!pC1 && pC2)
+              || ( pC1 && pC2  && (*pC1 < *pC2));
         }
     };
   
diff --git a/src/proc/control/command.cpp b/src/proc/control/command.cpp
index b6cf35cdd..b786142ff 100644
--- a/src/proc/control/command.cpp
+++ b/src/proc/control/command.cpp
@@ -90,7 +90,8 @@ namespace control {
     static format fmt("Command \"%s\" not found");
     if (!cmd)
       throw error::Invalid(str(fmt % cmdID), LUMIERA_ERROR_INVALID_COMMAND);
-      
+    
+    ENSURE (cmdID == CommandRegistry::instance().findDefinition(cmd));
     return cmd;
   }
   
diff --git a/src/proc/control/command.hpp b/src/proc/control/command.hpp
index 1549c09db..82f5b5cc3 100644
--- a/src/proc/control/command.hpp
+++ b/src/proc/control/command.hpp
@@ -264,7 +264,8 @@ namespace control {
   inline bool
   operator< (Command const& c1, Command const& c2)
   {
-    return ( c1 &&  c2  && (&c1.impl() < &c2.impl())); 
+    return (!c1 && c2)
+        || ( c1 && c2 && (&c1.impl() < &c2.impl())); 
   }