diff --git a/midas/checker/registry.py b/midas/checker/registry.py
index 3e3d509..fa2d1bd 100644
--- a/midas/checker/registry.py
+++ b/midas/checker/registry.py
@@ -7,6 +7,7 @@ from midas.checker.types import (
     AppliedType,
     BaseType,
     ComplexType,
+    ConstraintType,
     ExtensionType,
     Function,
     GenericType,
@@ -130,6 +131,9 @@ class TypesRegistry:
                     return False
                 return self.is_subtype(bound, type2)
 
+            case (ConstraintType(type=base1), _):
+                return self.is_subtype(base1, type2)
+
         return False
 
     # TODO: verify the logic in here