diff --git a/src/api/python/z3.py b/src/api/python/z3.py
index ff0bd6641..ce53a4c1f 100644
--- a/src/api/python/z3.py
+++ b/src/api/python/z3.py
@@ -4147,7 +4147,7 @@ class Datatype:
         """
         if __debug__:
             _z3_assert(isinstance(name, str), "String expected")
-            _z3_assert(name != "")
+            _z3_assert(name != "", "Constructor name cannot be empty")
         return self.declare_core(name, "is_" + name, *args)
 
     def __repr__(self):