diff --git a/pyk/src/pyk/kcfg/semantics.py b/pyk/src/pyk/kcfg/semantics.py
index 05134f82e00..9d8ab27e72f 100644
--- a/pyk/src/pyk/kcfg/semantics.py
+++ b/pyk/src/pyk/kcfg/semantics.py
@@ -21,6 +21,9 @@ def same_loop(self, c1: CTerm, c2: CTerm) -> bool: ...
     @abstractmethod
     def custom_step(self, c: CTerm) -> KCFGExtendResult | None: ...
 
+    @abstractmethod
+    def is_mergeable(self, c1: CTerm, c2: CTerm) -> bool: ...
+
 
 class DefaultSemantics(KCFGSemantics):
     def is_terminal(self, c: CTerm) -> bool:
@@ -34,3 +37,6 @@ def same_loop(self, c1: CTerm, c2: CTerm) -> bool:
 
     def custom_step(self, c: CTerm) -> KCFGExtendResult | None:
         return None
+
+    def is_mergeable(self, c1: CTerm, c2: CTerm) -> bool:
+        return False