diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 04bc82cc0..0b696a340 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -31,8 +31,10 @@ extern "C" {
 #include "command.hh"
 #include "finally.hh"
 
+#if HAVE_BOEHMGC
 #define GC_INCLUDE_NEW
 #include <gc/gc_cpp.h>
+#endif
 
 namespace nix {
 
@@ -44,7 +46,10 @@ namespace nix {
 #define ESC_CYA "\033[36m"
 #define ESC_END "\033[0m"
 
-struct NixRepl : gc
+struct NixRepl
+    #if HAVE_BOEHMGC
+    : gc
+    #endif
 {
     string curDir;
     EvalState state;