diff --git a/vyper/builtins/_signatures.py b/vyper/builtins/_signatures.py
index f955296ee0..0c65a0756f 100644
--- a/vyper/builtins/_signatures.py
+++ b/vyper/builtins/_signatures.py
@@ -83,6 +83,7 @@ class BuiltinFunctionT(VyperType):
     _has_varargs = False
     _inputs: list[tuple[str, Any]] = []
     _kwargs: dict[str, KwargSettings] = {}
+    _modifiability: Modifiability = Modifiability.MODIFIABLE
     _return_type: Optional[VyperType] = None
 
     # helper function to deal with TYPE_DEFINITIONs
diff --git a/vyper/builtins/functions.py b/vyper/builtins/functions.py
index a924a56010..2843b567e1 100644
--- a/vyper/builtins/functions.py
+++ b/vyper/builtins/functions.py
@@ -49,7 +49,7 @@
     UnfoldableNode,
     ZeroDivisionException,
 )
-from vyper.semantics.analysis.base import VarInfo
+from vyper.semantics.analysis.base import Modifiability, VarInfo
 from vyper.semantics.analysis.utils import (
     get_common_types,
     get_exact_type_from_node,
@@ -105,9 +105,8 @@
 class FoldedFunctionT(BuiltinFunctionT):
     # Base class for nodes which should always be folded
 
-    # Since foldable builtin functions are not folded before semantics validation,
-    # this flag is used for `check_modifiability` in semantics validation.
-    _kwargable = True
+    # This flag is used for `check_modifiability` in semantics validation.
+    _modifiability = Modifiability.ALWAYS_CONSTANT
 
 
 class TypenameFoldedFunctionT(FoldedFunctionT):
diff --git a/vyper/semantics/analysis/utils.py b/vyper/semantics/analysis/utils.py
index a7b62b9a7a..ebc4f27e84 100644
--- a/vyper/semantics/analysis/utils.py
+++ b/vyper/semantics/analysis/utils.py
@@ -648,8 +648,8 @@ def check_modifiability(node: vy_ast.VyperNode, modifiability: Modifiability) ->
             return all(check_modifiability(v, modifiability) for v in args[0].values)
 
         call_type = get_exact_type_from_node(node.func)
-        if getattr(call_type, "_kwargable", False):
-            return True
+        call_type_modifiability = getattr(call_type, "_modifiability", Modifiability.MODIFIABLE)
+        return call_type_modifiability >= modifiability
 
     value_type = get_expr_info(node)
     return value_type.modifiability >= modifiability