diff --git a/pyk/src/pyk/cterm/cterm.py b/pyk/src/pyk/cterm/cterm.py
index 10f9f1cb52..9b333db45e 100644
--- a/pyk/src/pyk/cterm/cterm.py
+++ b/pyk/src/pyk/cterm/cterm.py
@@ -333,8 +333,8 @@ def add_constraint(self, constraint: KInner) -> CSubst:
 
     def apply(self, cterm: CTerm) -> CTerm:
         """Apply this `CSubst` to the given `CTerm` (instantiating the free variables, and adding the constraints)."""
-        _kast = self.subst(cterm.kast)
-        return CTerm(_kast, [self.constraint])
+        config = self.subst(cterm.config)
+        return CTerm(config, [self.constraint])
 
 
 def cterm_build_claim(