diff --git a/internal/paramutil/sentinel.go b/internal/paramutil/sentinel.go
deleted file mode 100644
index db07a19..0000000
--- a/internal/paramutil/sentinel.go
+++ /dev/null
@@ -1,31 +0,0 @@
-package paramutil
-
-import (
-	"github.com/openai/openai-go/v3/internal/encoding/json/sentinel"
-)
-
-// NullPtr returns a pointer to the zero value of the type T.
-// When used with [MarshalObject] or [MarshalUnion], it will be marshaled as null.
-//
-// It is unspecified behavior to mutate the value pointed to by the returned pointer.
-func NullPtr[T any]() *T {
-	return sentinel.NullPtr[T]()
-}
-
-// IsNullPtr returns true if the pointer was created by [NullPtr].
-func IsNullPtr[T any](ptr *T) bool {
-	return sentinel.IsNullPtr(ptr)
-}
-
-// NullSlice returns a non-nil slice with a length of 0.
-// When used with [MarshalObject] or [MarshalUnion], it will be marshaled as null.
-//
-// It is undefined behavior to mutate the slice returned by [NullSlice].
-func NullSlice[T any]() []T {
-	return sentinel.NullSlice[T]()
-}
-
-// IsNullSlice returns true if the slice was created by [NullSlice].
-func IsNullSlice[T any](slice []T) bool {
-	return sentinel.IsNullSlice(slice)
-}