diff --git a/src/libexpr-c/nix_api_expr.cc b/src/libexpr-c/nix_api_expr.cc
index 8f21d7022..333e99460 100644
--- a/src/libexpr-c/nix_api_expr.cc
+++ b/src/libexpr-c/nix_api_expr.cc
@@ -16,8 +16,6 @@
 
 #if HAVE_BOEHMGC
 #  include <mutex>
-#  define GC_INCLUDE_NEW 1
-#  include "gc_cpp.h"
 #endif
 
 nix_err nix_libexpr_init(nix_c_context * context)