diff --git a/src/smt/theory_user_propagator.cpp b/src/smt/theory_user_propagator.cpp
index 06422cbf0..03ee6b687 100644
--- a/src/smt/theory_user_propagator.cpp
+++ b/src/smt/theory_user_propagator.cpp
@@ -218,8 +218,9 @@ bool theory_user_propagator::internalize_term(app* term)  {
     
     unsigned v = add_expr(term);
 
-    if (m_created_eh)
-        m_created_eh(m_user_context, this, term, v);
+    if (!m_created_eh)
+        throw default_exception("You have to register a created event handler for new terms");
+    m_created_eh(m_user_context, this, term, v);
     return true;
 }