diff --git a/src/libexpr/nix_api_expr.cc b/src/libexpr/nix_api_expr.cc
index df8a66053..46c8835f2 100644
--- a/src/libexpr/nix_api_expr.cc
+++ b/src/libexpr/nix_api_expr.cc
@@ -39,27 +39,15 @@ nix_err nix_libexpr_init(nix_c_context *context) {
   NIXC_CATCH_ERRS
 }
 
-Expr *nix_parse_expr_from_string(nix_c_context *context, State *state,
-                                 const char *expr, const char *path,
-                                 GCRef *ref) {
+nix_err nix_expr_eval_from_string(nix_c_context *context, State *state,
+                                  const char *expr, const char *path,
+                                  Value *value) {
   if (context)
     context->last_err_code = NIX_OK;
   try {
-    Expr *result = state->state.parseExprFromString(
+    nix::Expr *parsedExpr = state->state.parseExprFromString(
         expr, state->state.rootPath(nix::CanonPath(path)));
-    if (ref)
-      ref->ptr = result;
-    return result;
-  }
-  NIXC_CATCH_ERRS_NULL
-}
-
-nix_err nix_expr_eval(nix_c_context *context, State *state, Expr *expr,
-                      Value *value) {
-  if (context)
-    context->last_err_code = NIX_OK;
-  try {
-    state->state.eval((nix::Expr *)expr, *(nix::Value *)value);
+    state->state.eval(parsedExpr, *(nix::Value *)value);
   }
   NIXC_CATCH_ERRS
 }
diff --git a/src/libexpr/nix_api_expr.h b/src/libexpr/nix_api_expr.h
index f99fee1b1..e53aa5cd9 100644
--- a/src/libexpr/nix_api_expr.h
+++ b/src/libexpr/nix_api_expr.h
@@ -13,12 +13,6 @@ extern "C" {
 // cffi start
 
 // Type definitions
-/**
- * @brief Represents a parsed nix Expression, can be evaluated into a Value.
- *
- * Owned by the GC.
- */
-typedef void Expr; // nix::Expr
 /**
  * @brief Represents a nix evaluator state.
  *
@@ -54,34 +48,19 @@ typedef struct GCRef GCRef; // void*
 nix_err nix_libexpr_init(nix_c_context *context);
 
 /**
- * @brief Parses a Nix expression from a string.
- *
- * The returned expression is owned by the garbage collector.
- * Pass a gcref to keep a reference.
- *
- * @param[out] context Optional, stores error information
- * @param[in] state Evaluator state.
- * @param[in] expr The Nix expression to parse.
- * @param[in] path The file path to associate with the expression.
- * @param[out] ref Optional, will store a reference to the returned value.
- * @return A parsed expression or NULL on failure.
- */
-Expr *nix_parse_expr_from_string(nix_c_context *context, State *state,
-                                 const char *expr, const char *path,
-                                 GCRef *ref);
-
-/**
- * @brief Evaluates a parsed Nix expression.
+ * @brief Parses and evaluates a Nix expression from a string.
  *
  * @param[out] context Optional, stores error information
  * @param[in] state The state of the evaluation.
- * @param[in] expr The Nix expression to evaluate.
+ * @param[in] expr The Nix expression to parse.
+ * @param[in] path The file path to associate with the expression.
  * @param[out] value The result of the evaluation. You should allocate this
  * yourself.
  * @return NIX_OK if the evaluation was successful, an error code otherwise.
  */
-nix_err nix_expr_eval(nix_c_context *context, State *state, Expr *expr,
-                      Value *value);
+nix_err nix_expr_eval_from_string(nix_c_context *context, State *state,
+                                  const char *expr, const char *path,
+                                  Value *value);
 
 /**
  * @brief Calls a Nix function with an argument.
diff --git a/src/libexpr/nix_api_value.cc b/src/libexpr/nix_api_value.cc
index 4a4a56ac3..6a2f19de9 100644
--- a/src/libexpr/nix_api_value.cc
+++ b/src/libexpr/nix_api_value.cc
@@ -386,17 +386,6 @@ nix_err nix_copy_value(nix_c_context *context, Value *value, Value *source) {
   NIXC_CATCH_ERRS
 }
 
-nix_err nix_set_thunk(nix_c_context *context, State *s, Value *value,
-                      Expr *expr) {
-  if (context)
-    context->last_err_code = NIX_OK;
-  try {
-    auto &v = check_value_not_null(value);
-    s->state.mkThunk_(v, (nix::Expr *)expr);
-  }
-  NIXC_CATCH_ERRS
-}
-
 typedef std::shared_ptr<nix::BindingsBuilder> BindingsBuilder_Inner;
 
 nix_err nix_make_attrs(nix_c_context *context, Value *value,
diff --git a/src/libexpr/nix_api_value.h b/src/libexpr/nix_api_value.h
index 6d1604a6f..22ecfa86b 100644
--- a/src/libexpr/nix_api_value.h
+++ b/src/libexpr/nix_api_value.h
@@ -32,7 +32,6 @@ typedef enum {
 
 // forward declarations
 typedef void Value;
-typedef void Expr;
 typedef struct State State;
 typedef struct GCRef GCRef;
 // type defs
@@ -307,16 +306,6 @@ nix_err nix_set_primop(nix_c_context *context, Value *value, PrimOp *op);
  * @return error code, NIX_OK on success.
  */
 nix_err nix_copy_value(nix_c_context *context, Value *value, Value *source);
-/** @brief Make a thunk from an expr.
- *
- * Expr will be evaluated when the value is forced
- * @param[out] context Optional, stores error information
- * @param[out] value Nix value to modify
- * @param[in] expr the expr to thunk
- * @return error code, NIX_OK on success.
- */
-nix_err nix_set_thunk(nix_c_context *context, State *s, Value *value,
-                      Expr *expr);
 /**@}*/
 
 /** @brief Create a bindings builder