diff --git a/moo/lib/exec.c b/moo/lib/exec.c
index 4063fde..f560ba6 100644
--- a/moo/lib/exec.c
+++ b/moo/lib/exec.c
@@ -1776,21 +1776,26 @@ moo_oop_method_t moo_findmethod (moo_t* moo, moo_oop_t receiver, moo_oop_char_t
 		 * otherwise c points to a class object */
 	}
 
-#if 0
-	mcidx = ((moo_oow_t)c + (moo_oow_t)selector) % MOO_METHOD_CACHE_SIZE; /* TODO: change hash function */
+	/*mcidx = MOO_HASH_INIT;
+	mcidx = MOO_HASH_VALUE(mcidx, (moo_oow_t)c);
+	mcidx = MOO_HASH_VALUE(mcidx, (moo_oow_t)selector);
+	mcidx &= (MOO_METHOD_CACHE_SIZE - 1);*/
+	/*mcidx = ((moo_oow_t)c + (moo_oow_t)selector) % MOO_METHOD_CACHE_SIZE; */
+	mcidx = ((moo_oow_t)_class ^ (moo_oow_t)selector) & (MOO_METHOD_CACHE_SIZE - 1);
 	mcitm = &moo->method_cache[mcidx];
 	
 	if (mcitm->receiver_class == c  && mcitm->selector == selector && mcitm->method_type == mth_type)
 	{
-		/* cache  hit */
+		/* cache hit */
+		/* TODO: moo->method_cache_hits++; */
 		return mcitm->method;
 	}
-#endif
 	
 	/* [IMPORT] the method lookup logic should be the same as ciim_on_each_method() in comp.c */
 	mth = find_method_in_class_chain(moo, c, mth_type, &message);
 	if (mth) 
 	{
+		/* TODO: moo->method_cache_misses++; */
 		mcitm->receiver_class = c;
 		mcitm->selector = selector;
 		mcitm->method_type = mth_type;
@@ -1803,19 +1808,26 @@ not_found:
 	{
 		/* the object is an instance of Class. find the method
 		 * in an instance method dictionary of Class also */
-#if 0
-		mcidx = ((moo_oow_t)_class + (moo_oow_t)selector) % MOO_METHOD_CACHE_SIZE; /* TODO: change hash function */
+		
+		/*mcidx = MOO_HASH_INIT;
+		mcidx = MOO_HASH_VALUE(mcidx, (moo_oow_t)_class);
+		mcidx = MOO_HASH_VALUE(mcidx, (moo_oow_t)selector);
+		mcidx &= (MOO_METHOD_CACHE_SIZE - 1); */
+		/* mcidx = ((moo_oow_t)_class + (moo_oow_t)selector) % MOO_METHOD_CACHE_SIZE; */
+		mcidx = ((moo_oow_t)_class ^ (moo_oow_t)selector) & (MOO_METHOD_CACHE_SIZE - 1);
 		mcitm = &moo->method_cache[mcidx];
 
 		if (mcitm->receiver_class == _class  && mcitm->selector == selector && mcitm->method_type == MOO_METHOD_INSTANCE)
 		{
 			/* cache  hit */
+			/* TODO: moo->method_cache_hits++; */
 			return mcitm->method;
 		}
-#endif	
+		
 		mth = find_method_in_class(moo, _class, MOO_METHOD_INSTANCE, &message);
 		if (mth) 
 		{
+			/* TODO: moo->method_cache_misses++; */
 			mcitm->receiver_class = c;
 			mcitm->selector = selector;
 			mcitm->method_type = MOO_METHOD_INSTANCE;
@@ -1829,6 +1841,11 @@ not_found:
 	return MOO_NULL;
 }
 
+void moo_clearmethodcache (moo_t* moo)
+{
+	MOO_MEMSET (moo->method_cache, 0, MOO_SIZEOF(moo->method_cache));
+}
+
 static int start_initial_process_and_context (moo_t* moo, const moo_oocs_t* objname, const moo_oocs_t* mthname)
 {
 	/* the initial context is a fake context. if objname is 'Stix' and
@@ -6028,6 +6045,8 @@ int moo_invoke (moo_t* moo, const moo_oocs_t* objname, const moo_oocs_t* mthname
 	MOO_ASSERT (moo, moo->active_context == MOO_NULL);
 	MOO_ASSERT (moo, moo->active_method == MOO_NULL);
 
+	moo_clearmethodcache (moo);
+
 	if (start_initial_process_and_context(moo, objname, mthname) <= -1) return -1;
 	moo->initial_context = moo->processor->active->initial_context;
 
diff --git a/moo/lib/gc.c b/moo/lib/gc.c
index c81c9bf..c3c5ac5 100644
--- a/moo/lib/gc.c
+++ b/moo/lib/gc.c
@@ -1039,6 +1039,9 @@ void moo_gc (moo_t* moo)
 	if (moo->active_method) moo->active_code = MOO_METHOD_GET_CODE_BYTE(moo->active_method); /* update moo->active_code */
 	if (gcfin_count > 0) moo->sem_gcfin_sigreq = 1;
 
+	/* invalidate method cache. TODO: GCing entries on the method cache is also one way instead of full invalidation */
+	moo_clearmethodcache (moo);
+	
 	/* TODO: include some gc statstics like number of live objects, gc performance, etc */
 	MOO_LOG4 (moo, MOO_LOG_GC | MOO_LOG_INFO, 
 		"Finished GC curheap base %p ptr %p newheap base %p ptr %p\n",
diff --git a/moo/lib/moo-prv.h b/moo/lib/moo-prv.h
index 2bd1174..a4a5313 100644
--- a/moo/lib/moo-prv.h
+++ b/moo/lib/moo-prv.h
@@ -1508,6 +1508,9 @@ moo_pfbase_t* moo_getpfnum (
 	moo_ooi_t*        pfnum
 );
 
+void moo_clearmethodcache (
+	moo_t*            moo
+);
 moo_oop_method_t moo_findmethod (
 	moo_t*            moo,
 	moo_oop_t         receiver,
diff --git a/moo/lib/moo.h b/moo/lib/moo.h
index bfb100d..eb532c7 100644
--- a/moo/lib/moo.h
+++ b/moo/lib/moo.h
@@ -1336,6 +1336,7 @@ struct moo_method_cache_item_t
 };
 typedef struct moo_method_cache_item_t moo_method_cache_item_t;
 
+/* it must be a power of 2. otherwise cache hash will fail miserably */
 #define MOO_METHOD_CACHE_SIZE 4096
 
 /* =========================================================================