diff --git a/doc/ref_internals.rst b/doc/ref_internals.rst
index 86e2edad2fd291489fdc1a698d6a069899acf4bb..0ad56a39bb1f63a9c1ce1071909ea0f53ebd4fd4 100644
--- a/doc/ref_internals.rst
+++ b/doc/ref_internals.rst
@@ -24,6 +24,11 @@ the codegen pipeline user-provided types are converted to
 
 .. automodule:: loopy.types
 
+Type inference
+^^^^^^^^^^^^^^
+
+.. automodule:: loopy.type_inference
+
 Codegen
 -------
 
diff --git a/loopy/target/c/codegen/expression.py b/loopy/target/c/codegen/expression.py
index b1723e9d6bf19701b47853638cbf90e1d70a5ee0..83c13dfe549d905d0f63c9f2a082a3c679c9e8c8 100644
--- a/loopy/target/c/codegen/expression.py
+++ b/loopy/target/c/codegen/expression.py
@@ -48,12 +48,13 @@ from pymbolic.mapper.stringifier import (
 from loopy.diagnostic import LoopyError
 from loopy.expression import dtype_to_type_context
 from loopy.target.c import CExpression
-from loopy.type_inference import TypeReader
+from loopy.type_inference import TypeInferenceMapper, TypeReader
 from loopy.types import LoopyType
 from loopy.typing import Expression, is_integer
 
 
 if TYPE_CHECKING:
+    from loopy.codegen import CodeGenerationState
     from loopy.symbolic import TypeCast
 
 
@@ -79,7 +80,11 @@ class ExpressionToCExpressionMapper(IdentityMapper):
           expected type for untyped expressions such as python scalars. The
           type of the expressions takes precedence over *type_context*.
     """
-    def __init__(self, codegen_state, fortran_abi=False, type_inf_mapper=None):
+    def __init__(self,
+                 codegen_state: CodeGenerationState,
+                 fortran_abi: bool = False,
+                 type_inf_mapper: TypeInferenceMapper | None = None
+             ) -> None:
         self.kernel = codegen_state.kernel
         self.codegen_state = codegen_state
 
diff --git a/loopy/type_inference.py b/loopy/type_inference.py
index b3c6ffddd40e84354ab927f3c2c535bf0c9a675c..8894af573ede6377a8621da3904661a980782aa2 100644
--- a/loopy/type_inference.py
+++ b/loopy/type_inference.py
@@ -1,3 +1,7 @@
+"""
+.. autoclass:: TypeInferenceMapper
+"""
+
 from __future__ import annotations