diff --git a/build-aux/pointer.sh b/build-aux/pointer.sh
index ab7683ce..38a19e89 100755
--- a/build-aux/pointer.sh
+++ b/build-aux/pointer.sh
@@ -63,4 +63,5 @@ sed -ri                                                         \
     src/struct.c                                                \
     src/symbol.c                                                \
     src/vector.c                                                \
-    simple.make
+    src/test/gc.c                                               \
+    simple.make                                                 \
diff --git a/simple.make b/simple.make
index 227eecc3..08c2a977 100644
--- a/simple.make
+++ b/simple.make
@@ -52,7 +52,7 @@ CFLAGS:=					\
  -Wno-incompatible-pointer-types		\
  -Wno-int-conversion
 
-MES_SOURCES =					\
+LIBMES_SOURCES =				\
  src/builtins.c					\
  src/core.c					\
  src/display.c					\
@@ -61,7 +61,6 @@ MES_SOURCES =					\
  src/hash.c					\
  src/lib.c					\
  src/math.c					\
- src/mes.c					\
  src/module.c					\
  src/posix.c					\
  src/reader.c					\
@@ -71,6 +70,14 @@ MES_SOURCES =					\
  src/symbol.c					\
  src/vector.c
 
+MES_SOURCES =					\
+ $(LIBMES_SOURCES)				\
+ src/mes.c
+
+TEST_GC_SOURCES =				\
+ $(LIBMES_SOURCES)				\
+ src/test/gc.c
+
 M2_SOURCES =					\
  lib/linux/x86-mes-m2/crt1.c			\
  lib/linux/x86-mes-m2/_exit.c			\
@@ -168,9 +175,15 @@ GCC_SOURCES =					\
 mes-gcc: bin/mes-gcc
 mes-m2: bin/mes-m2
 
+gc-gcc: bin/gc-gcc
+gc-m2: bin/gc-m2
+
 bin/mes-gcc: simple.make $(GCC_SOURCES) $(MES_SOURCES) $(INCLUDES) | bin
 	$(CC) $(CFLAGS) $(GCC_SOURCES) $(MES_SOURCES) -o $@
 
+bin/gc-gcc: simple.make $(GCC_SOURCES) $(TEST_GC_SOURCES) $(INCLUDES) | bin
+	$(CC) $(CFLAGS) -D GC_TEST=1 $(GCC_SOURCES) $(TEST_GC_SOURCES) -o $@
+
 M2_PLANET_INCLUDES =				\
  include/m2/lib.h				\
  include/linux/x86/syscall.h			\
diff --git a/src/gc.c b/src/gc.c
index 4d994aae..bb473efe 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -294,7 +294,7 @@ gc_init_news ()
 #else
   g_news = g_cells + g_free;
   NTYPE (cell_arena) = TVECTOR;
-  NLENGTH (cell_arena) = 1000;
+  NLENGTH (cell_arena) = LENGTH (cell_arena - 1);
   NVECTOR (cell_arena) = 0;
   g_news = g_news + 1;
   NTYPE (cell_arena) = TCHAR;
diff --git a/src/test/gc.c b/src/test/gc.c
new file mode 100644
index 00000000..bac4c7b2
--- /dev/null
+++ b/src/test/gc.c
@@ -0,0 +1,46 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mes/lib.h"
+#include "mes/mes.h"
+
+#include <stdlib.h>
+
+int g_debug;
+
+int
+main (int argc, char **argv, char **envp)
+{
+  char *p;
+  if (p = getenv ("MES_DEBUG"))
+    g_debug = atoi (p);
+  gc_init ();
+
+  SCM v = -1;
+  LENGTH (v) = 10;
+  eputs ("arena: "); write_ (v); eputs ("\n");
+  gc_stats_ ("0");
+  gc_ ();
+  v = -1;
+  eputs ("arena: "); write_ (v); eputs ("\n");
+  gc_stats_ ("1");
+
+  return 0;
+}