diff --git a/Makefile b/Makefile
index b82dc91..6b71f05 100644
--- a/Makefile
+++ b/Makefile
@@ -44,7 +44,7 @@ TESTS_PY_FILES=$(wildcard tests/*.py)
 # rule to make objects for static linkage
 .objs/%.o : %.c
 	@mkdir -p $(dir $@)
-	$(CC) $(CFLAGS) -g -O0 -I . -c -o $@ $<
+	$(CC) $(CFLAGS) -DNDEBUG -g -O0 -I . -c -o $@ $<
 
 .dbgobjs/%.o : %.c
 	@mkdir -p $(dir $@)
@@ -53,7 +53,7 @@ TESTS_PY_FILES=$(wildcard tests/*.py)
 # rule to make objects for dynamic linkage
 .dynobjs/%.o : %.c
 	@mkdir -p $(dir $@)
-	$(CC) $(CFLAGS) -fPIC -g -O0 -I . -c -o $@ $<
+	$(CC) $(CFLAGS) -DNDEBUG -fPIC -g -O0 -I . -c -o $@ $<
 
 
 all: tpy tpvm
@@ -97,7 +97,7 @@ GENERATED_SOURCE_FILES+=tinypy/tp_opcodes.h
 
 # tpvm only takes compiled byte codes (.tpc files)
 tpvm : $(VMLIB_FILES:%.c=.objs/tinypy/%.o) .objs/tinypy/vmmain.o modules/modules.a
-	$(CC) $(CFLAGS) -g -O0 -o $@ $^ -lm
+	$(CC) $(CFLAGS) -DNDEBUG -g -O0 -o $@ $^ -lm
 #
 # tpvm only takes compiled byte codes (.tpc files)
 tpvm-dbg : $(VMLIB_FILES:%.c=.dbgobjs/tinypy/%.o) .dbgobjs/tinypy/vmmain.o modules/modules.a
@@ -105,7 +105,7 @@ tpvm-dbg : $(VMLIB_FILES:%.c=.dbgobjs/tinypy/%.o) .dbgobjs/tinypy/vmmain.o modul
 
 # tpy takes .py files
 tpy : $(TPLIB_FILES:%.c=.objs/tinypy/%.o) .objs/tinypy/tpmain.o modules/modules.a
-	$(CC) $(CFLAGS) -o $@ $^ -lm
+	$(CC) $(CFLAGS) -DNDEBUG -o $@ $^ -lm
 
 # tpy takes .py files
 tpy-dbg : $(TPLIB_FILES:%.c=.dbgobjs/tinypy/%.o) .dbgobjs/tinypy/tpmain.o modules/modules.a
diff --git a/modules/re/regexpr.h b/modules/re/regexpr.h
index 2aee62d..feac7dc 100644
--- a/modules/re/regexpr.h
+++ b/modules/re/regexpr.h
@@ -137,11 +137,11 @@ void re_compile_fastmap(regexp_t compiled);
 extern int re_syntax;
 extern unsigned char re_syntax_table[256];
 void re_compile_initialize();
-int re_set_syntax();
-char *re_compile_pattern();
-int re_match();
-int re_search();
-void re_compile_fastmap();
+int re_set_syntax(int);
+char *re_compile_pattern(unsigned char*, int, regexp_t);
+int re_match(regexp_t, unsigned char*, int, int, regexp_registers_t);
+int re_search(regexp_t, unsigned char*, int, int, int, regexp_registers_t);
+void re_compile_fastmap(regexp_t);
 
 #endif /* HAVE_PROTOTYPES */
 
diff --git a/tests/test_gc.py b/tests/test_gc.py
new file mode 100644
index 0000000..ab889f0
--- /dev/null
+++ b/tests/test_gc.py
@@ -0,0 +1,41 @@
+from tinypy.runtime.testing import UnitTest
+
+class Create:
+    def __init__(self, **args):
+        self.__dict__.update(args)
+
+    def _create_with_a(a):
+        return Create(a=a)
+    create_with_a = staticmethod(_create_with_a)
+
+    def _create_with_b(b):
+        return Create(b=b)
+    create_with_b = staticmethod(_create_with_b)
+
+
+class GcTest(UnitTest):
+    objA = None
+    objB = None
+    scrap_objects = []
+
+    def test_create(self):
+        self.objA = Create.create_with_a(3)
+        assert self.objA.a == 3
+        self.objB = Create.create_with_b(3)
+        assert self.objB.b == 3
+
+    def test_delete(self):
+        assert self.objA is not None
+        assert self.objB is not None
+        for i in range(20):
+            new_obj = Create(a=i)
+            self.scrap_objects.append(new_obj)
+        del self.objA
+        del self.objB
+        #assert self.objA is None
+        #assert self.objB is None
+
+
+t = GcTest()
+
+t.run()
diff --git a/tinypy/tp_gc.c b/tinypy/tp_gc.c
index b10157a..075d91d 100644
--- a/tinypy/tp_gc.c
+++ b/tinypy/tp_gc.c
@@ -21,6 +21,15 @@
 #define TP_GC_TRACE 0
 #define TP_GC_ASSERT_LISTS_ARE_DISJOINT 0    /* Assert no white object is on the black list. Very slow. */
 
+/* Maximum number of objects to collect per partial GC run. */
+#define TP_GC_STEP_MAX 8
+
+/* Macros for min/max, borrowed from glibc sys/param.h */
+#ifndef MAX
+#define MIN(a,b) (((a)<(b))?(a):(b))
+#define MAX(a,b) (((a)>(b))?(a):(b))
+#endif
+
 /* tp_grey: ensure an object to the grey list, if the object is already
  * marked grey, then do nothing. */
 void tp_grey(TP, tp_obj v) {
@@ -196,8 +205,14 @@ void tp_collect(TP) {
     tp->black->len = 0;
 }
 
-void tp_mark(TP, int max) {
-    while (tp->grey->len && max > 0) {
+void tp_mark(TP, int gc_max) {
+    int target_len = gc_max > 0 ? MAX(0, tp->grey->len - gc_max) : 0;
+    DEBUG_PRINTF(
+        "GC: Coloring objects, %d out of %d to mark\n",
+        tp->grey->len - target_len, tp->grey->len
+    );
+
+    while (tp->grey->len > target_len) {
         tp_obj v;
         /* pick a grey object */
         v = tpd_list_pop(tp, tp->grey, tp->grey->len-1, "_tp_gcinc");
@@ -214,8 +229,8 @@ void tp_mark(TP, int max) {
 
         /* put children to grey. */
         tp_follow(tp,v);
-        if(max > 0) max--;
     }
+    DEBUG_PRINTF("GC complete, %d items remaining\n", tp->grey->len);
 }
 
 void tp_gc_dump(TP, tpd_list * l, int name, int mark) {
@@ -242,10 +257,12 @@ void tp_gc_dump(TP, tpd_list * l, int name, int mark) {
 
 void tp_gc_run(TP, int full) {
     if (full || tp->gcmax == 0 || (tp->steps % tp->gcmax == 0)) {
+        DEBUG_PRINTF("Running full GC\n");
         tp_mark(tp, -1);
     } else {
-        /* mark 2 items from the grey list every step */
-        tp_mark(tp, 8);
+        /* mark a fixed number of items from the grey list every step */
+        DEBUG_PRINTF("Running partial GC of up to %d items\n", TP_GC_STEP_MAX);
+        tp_mark(tp, TP_GC_STEP_MAX);
     }
 
     /* grey list is empty, we can run a collection */
@@ -286,4 +303,3 @@ void tp_gc_deinit(TP) {
 
 
 /**/
-
diff --git a/tinypy/tp_internal.h b/tinypy/tp_internal.h
index 82e09d1..f4889b5 100644
--- a/tinypy/tp_internal.h
+++ b/tinypy/tp_internal.h
@@ -25,3 +25,11 @@ tp_inline static tpd_frame * tp_get_cur_frame(TP) { return tp_get_frame(tp, tp->
 
 /* Detect unintended size changes. Update as needed. */
 STATIC_ASSERT(sizeof(tpd_code) == 4, "size of tpd_code must be 4");
+
+#ifndef DEBUG_PRINTF
+#ifdef NDEBUG
+#define DEBUG_PRINTF(...) {0;}
+#else
+#define DEBUG_PRINTF(...) fprintf(stderr, __VA_ARGS__)
+#endif
+#endif