diff --git a/libs/langgraph/langgraph/constants.py b/libs/langgraph/langgraph/constants.py
index 80713b839..4c6733ac5 100644
--- a/libs/langgraph/langgraph/constants.py
+++ b/libs/langgraph/langgraph/constants.py
@@ -1,6 +1,6 @@
 import sys
 from types import MappingProxyType
-from typing import Any, Mapping
+from typing import Any, Literal, Mapping, cast
 
 from langgraph.types import Interrupt, Send  # noqa: F401
 
@@ -73,7 +73,7 @@ NS_SEP = sys.intern("|")
 # for checkpoint_ns, separates each level (ie. graph|subgraph|subsubgraph)
 NS_END = sys.intern(":")
 # for checkpoint_ns, for each level, separates the namespace from the task_id
-CONF = sys.intern("configurable")
+CONF = cast(Literal["configurable"], sys.intern("configurable"))
 # key for the configurable dict in RunnableConfig
 
 RESERVED = {
diff --git a/libs/langgraph/langgraph/utils/config.py b/libs/langgraph/langgraph/utils/config.py
index 4261fc47c..6f75c64ba 100644
--- a/libs/langgraph/langgraph/utils/config.py
+++ b/libs/langgraph/langgraph/utils/config.py
@@ -83,9 +83,9 @@ def merge_configs(*configs: Optional[RunnableConfig]) -> RunnableConfig:
                     base[key] = value  # type: ignore[literal-required]
             elif key == CONF:
                 if base_value := base.get(key):
-                    base[key] = {**base_value, **value}  # type: ignore
+                    base[key] = {**base_value, **value}  # type: ignore[dict-item]
                 else:
-                    base[key] = value  # type: ignore[literal-required]
+                    base[key] = value
             elif key == "callbacks":
                 base_callbacks = base.get("callbacks")
                 # callbacks can be either None, list[handler] or manager