diff --git a/src/pdl/pdl_context.py b/src/pdl/pdl_context.py
index 074decd3c..e59b0e080 100644
--- a/src/pdl/pdl_context.py
+++ b/src/pdl/pdl_context.py
@@ -2,7 +2,7 @@
 from enum import StrEnum
 from typing import Any, Callable
 
-from .pdl_lazy import PdlApply, PdlDict, PdlLazy, PdlList
+from .pdl_lazy import PdlApply, PdlConst, PdlDict, PdlLazy, PdlList
 
 # def _default(self, obj):
 #    return getattr(obj.__class__, "to_json", _default.default)(obj) # pyright: ignore
@@ -136,6 +136,20 @@ def __repr__(self):  # pyright: ignore
         return ret + "]"
 
 
+def ensure_context(context: dict | list | PDLContext) -> PDLContext:
+    ctx: PDLContext
+    match context:
+        case dict():
+            ctx = SingletonContext(PdlConst(context))
+        case list():
+            ctx = DependentContext([ensure_context(c) for c in context])
+        case PDLContext():
+            ctx = context
+        case _:
+            raise TypeError(f"'{type(context)}' object is not a valid context")
+    return ctx
+
+
 def deserialize(
     context: list[dict[str, Any]],
 ) -> DependentContext:  # Only support dependent for now
diff --git a/src/pdl/pdl_interpreter.py b/src/pdl/pdl_interpreter.py
index 7dd55cb4c..9c9718202 100644
--- a/src/pdl/pdl_interpreter.py
+++ b/src/pdl/pdl_interpreter.py
@@ -101,6 +101,7 @@
     SingletonContext,
     add_done_callback,
     deserialize,
+    ensure_context,
 )
 from .pdl_dumper import as_json, block_to_dict  # noqa: E402
 from .pdl_lazy import PdlConst, PdlDict, PdlLazy, PdlList, lazy_apply  # noqa: E402
@@ -1413,23 +1414,28 @@ def process_call_model(
         scope,
         loc,
     )
-    model_input_result = model_input_future.result()
-    if isinstance(model_input_result, str):
-        model_input = [{"role": state.role, "content": model_input_result}]
-    else:
-        if isinstance(block, LitellmModelBlock):
-            model_input = model_input_result.serialize(SerializeMode.LITELLM)
-        else:
-            model_input = model_input_result.serialize(SerializeMode.GRANITEIO)
-    concrete_block = concrete_block.model_copy(
-        update={
-            "pdl__model_input": model_input,
-        }
-    )
-
-    model_input = [{k: v for k, v in m.items() if k != "defsite"} for m in model_input]
-    # Execute model call
     try:
+        model_input_result = model_input_future.result()
+        if isinstance(model_input_result, str):
+            model_input_result = [{"role": state.role, "content": model_input_result}]
+        model_input_context = ensure_context(model_input_result)
+        match block:
+            case LitellmModelBlock():
+                model_input = model_input_context.serialize(SerializeMode.LITELLM)
+            case GraniteioModelBlock():
+                model_input = model_input_context.serialize(SerializeMode.GRANITEIO)
+            case _:
+                assert False
+        concrete_block = concrete_block.model_copy(
+            update={
+                "pdl__model_input": model_input,
+            }
+        )
+        model_input = [
+            {k: v for k, v in m.items() if k != "defsite"} for m in model_input
+        ]
+
+        # Execute model call
         litellm_params = {}
 
         def get_transformed_inputs(kwargs):