diff --git a/gc.c b/gc.c
index a304241d..88fcca86 100644
--- a/gc.c
+++ b/gc.c
@@ -435,12 +435,7 @@ void sexp_mark_global_symbols(sexp ctx) {
 #endif
 
 sexp sexp_gc (sexp ctx, size_t *sum_freed) {
-  sexp res;
-#ifdef __GNUC__
-  sexp finalized __attribute__((unused));
-#else
-  sexp finalized;
-#endif
+  sexp res, finalized SEXP_NO_WARN_UNUSED;
   sexp_debug_printf("%p (heap: %p size: %lu)", ctx, sexp_context_heap(ctx),
                     sexp_heap_total_size(sexp_context_heap(ctx)));
   sexp_mark_global_symbols(ctx);
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 2b8a2593..7783a04b 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -45,6 +45,12 @@ extern "C" {
 #define sexp_out_of_file_descriptors() (0)
 #endif
 
+#ifdef __GNUC__
+#define SEXP_NO_WARN_UNUSED __attribute__((unused))
+#else
+#define SEXP_NO_WARN_UNUSED
+#endif
+
 #ifdef PLAN9
 #include <u.h>
 #include <libc.h>