diff --git a/lib/comp.c b/lib/comp.c
index 27e2459..f31dd81 100644
--- a/lib/comp.c
+++ b/lib/comp.c
@@ -4279,7 +4279,8 @@ static int compile_cons_xlist_expression (hcl_t* hcl, hcl_cnode_t* obj, int nret
 					if (nargs < sdv->slot[1] || nargs > sdv->slot[2])
 					{
 						hcl_setsynerrbfmt (hcl, HCL_SYNERR_ARGCOUNT, HCL_CNODE_GET_LOC(car), HCL_NULL,
-							"parameters count(%zd) mismatch in function call - %.*js - expecting %zu-%zu parameters", nargs, HCL_CNODE_GET_TOKLEN(car), HCL_CNODE_GET_TOKPTR(car), sdv->slot[1], sdv->slot[2]);
+							"parameters count(%zd) mismatch in function call - %.*js - expecting %zu-%zu parameters",
+							nargs, HCL_CNODE_GET_TOKLEN(car), HCL_CNODE_GET_TOKPTR(car), sdv->slot[1], sdv->slot[2]);
 						return -1;
 					}
 				}
diff --git a/lib/exec.c b/lib/exec.c
index 6c301f7..abf127a 100644
--- a/lib/exec.c
+++ b/lib/exec.c
@@ -2135,7 +2135,7 @@ static HCL_INLINE int call_primitive (hcl_t* hcl, hcl_ooi_t nargs)
 
 	rcv = (hcl_oop_prim_t)HCL_STACK_GETOP(hcl, nargs);
 	HCL_ASSERT (hcl, HCL_IS_PRIM(hcl, rcv));
-	HCL_ASSERT (hcl, HCL_OBJ_GET_SIZE(rcv) == HCL_PRIM_NUM_WORDS);
+	HCL_ASSERT (hcl, HCL_OBJ_GET_SIZE(rcv) == HCL_PRIM_NAMED_INSTVARS);
 
 	if (nargs < rcv->min_nargs && nargs > rcv->max_nargs)
 	{
@@ -3432,6 +3432,8 @@ static int execute (hcl_t* hcl)
 				b1 = bcode & 0x7; /* low 3 bits */
 			store_instvar:
 				LOG_INST_2 (hcl, "store_into_ivar %zu ## [%zd]", b1, HCL_OOP_TO_SMOOI(hcl->active_context/*->mthhome*/->ivaroff));
+	/* TODO: support if the receiver is an object with named/flexi pure-numeric fields (e.g. word, byte, etc).
+	 *       the following assertion must be lifted... */
 				HCL_ASSERT (hcl, HCL_OBJ_GET_FLAGS_TYPE(hcl->active_context->receiver) == HCL_OBJ_TYPE_OOP);
 				b1 += HCL_OOP_TO_SMOOI(hcl->active_context/*->mthhome*/->ivaroff);
 				((hcl_oop_oop_t)hcl->active_context->receiver)->slot[b1] = HCL_STACK_GETTOP(hcl);
diff --git a/lib/gc.c b/lib/gc.c
index baeb270..9b0d561 100644
--- a/lib/gc.c
+++ b/lib/gc.c
@@ -141,8 +141,8 @@ enum {
 	KCI_CONS,
 	KCI_METHOD_DICTIONARY,
 	KCI_FUNCTION,
+	KCI_PRIMITIVE,
 	KCI_COMPILED_BLOCK,
-	KCI_METHOD_CONTEXT,
 	KCI_BLOCK_CONTEXT,
 	KCI_PROCESS,
 	KCI_SEMAPHORE,
@@ -448,15 +448,17 @@ static kernel_class_info_t kernel_classes[__KCI_MAX__] =
 		HCL_OFFSETOF(hcl_t, c_function)
 	},
 
-#if 0
-	{ "Primitive", HCL_BRAND_PRIM,
-	  0,
-	  0,
-	  HCL_PRIM_NAMED_INSTVARS,
-	  0,
-	  HCL_OBJ_TYPE_OOP,
-	  HCL_OFFSETOF(hcl_t, c_prim) },
-#endif
+	KCI(KCI_PRIMITIVE) {
+		"Primitive",
+		KCI_OBJECT,
+		HCL_BRAND_PRIM,
+		0,
+		0,
+		HCL_PRIM_NAMED_INSTVARS,
+		0,
+		HCL_OBJ_TYPE_WORD,
+		HCL_OFFSETOF(hcl_t, c_primitive)
+	},
 
 	KCI(KCI_COMPILED_BLOCK) {
 		"CompiledBlock",
@@ -470,18 +472,6 @@ static kernel_class_info_t kernel_classes[__KCI_MAX__] =
 		HCL_OFFSETOF(hcl_t, c_block)
 	},
 
-	KCI(KCI_METHOD_CONTEXT) {
-		"MethodContext",
-		KCI_OBJECT,
-		0,
-		HCL_CLASS_SELFSPEC_FLAG_FINAL | HCL_CLASS_SELFSPEC_FLAG_LIMITED,
-		0,
-		HCL_CONTEXT_NAMED_INSTVARS,
-		HCL_CLASS_SPEC_FLAG_INDEXED,
-		HCL_OBJ_TYPE_OOP,
-		HCL_OFFSETOF(hcl_t, c_method_context)
-	},
-
 	KCI(KCI_BLOCK_CONTEXT) {
 		"BlockContext",
 		KCI_OBJECT,
diff --git a/lib/hcl.h b/lib/hcl.h
index 5aa2a4f..5cc6b59 100644
--- a/lib/hcl.h
+++ b/lib/hcl.h
@@ -531,7 +531,7 @@ struct hcl_trailer_t
 #define HCL_OBJ_GET_TRAILER_BYTE(oop) ((hcl_oob_t*)&((hcl_oop_oop_t)oop)->slot[HCL_OBJ_GET_SIZE(oop) + 1])
 #define HCL_OBJ_GET_TRAILER_SIZE(oop) ((hcl_oow_t)((hcl_oop_oop_t)oop)->slot[HCL_OBJ_GET_SIZE(oop)])
 
-#define HCL_PRIM_NUM_WORDS 4
+#define HCL_PRIM_NAMED_INSTVARS 4
 typedef struct hcl_prim_t hcl_prim_t;
 typedef struct hcl_prim_t* hcl_oop_prim_t;
 struct hcl_prim_t
@@ -1737,7 +1737,6 @@ struct hcl_t
 	hcl_oop_class_t c_primitive; /* Primitive */
 	hcl_oop_class_t c_block; /* CompiledBlock */
 
-	hcl_oop_class_t c_method_context; /* MethodContext */
 	hcl_oop_class_t c_block_context; /* BlockContext */
 	hcl_oop_class_t c_process; /* Process */
 	hcl_oop_class_t c_semaphore; /* Semaphore */
@@ -2090,12 +2089,22 @@ typedef enum hcl_concode_t hcl_concode_t;
 /*#define HCL_IS_SYMBOL(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_SYMBOL)*/
 #define HCL_IS_SYMBOL(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_symbol)
 
-#define HCL_IS_CONTEXT(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_CONTEXT)
-#define HCL_IS_FUNCTION(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_FUNCTION)
-#define HCL_IS_BLOCK(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_BLOCK)
-#define HCL_IS_CLASS(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_CLASS)
+/*#define HCL_IS_STRING(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_STRING)*/
+#define HCL_IS_STRING(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_string)
+
+/*#define HCL_IS_CONTEXT(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_CONTEXT)*/
+#define HCL_IS_CONTEXT(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_block_context)
+
+/*#define HCL_IS_FUNCTION(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_FUNCTION)*/
+#define HCL_IS_FUNCTION(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_function)
+
+/*#define HCL_IS_BLOCK(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_BLOCK)*/
+#define HCL_IS_BLOCK(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_block)
+
+/*#define HCL_IS_CLASS(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_CLASS)*/
+#define HCL_IS_CLASS(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_class)
+
 #define HCL_IS_INSTANCE(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_INSTANCE)
-#define HCL_IS_PROCESS(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_PROCESS)
 
 /*#define HCL_IS_CONS(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_CONS)*/
 #define HCL_IS_CONS(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_cons)
@@ -2110,12 +2119,14 @@ typedef enum hcl_concode_t hcl_concode_t;
 /*#define HCL_IS_DIC(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_DIC)*/
 #define HCL_IS_DIC(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_dictionary)
 
-#define HCL_IS_PRIM(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_PRIM)
+/*#define HCL_IS_PRIM(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_PRIM)*/
+#define HCL_IS_PRIM(hcl,v) (HCL_CLASSOF(hcl,v) == (hcl_oop_t)hcl->c_primitive)
+
 #define HCL_IS_PBIGINT(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_PBIGINT)
 #define HCL_IS_NBIGINT(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_NBIGINT)
 #define HCL_IS_BIGINT(hcl,v) (HCL_OOP_IS_POINTER(v) && (HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_PBIGINT || HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_NBIGINT))
-#define HCL_IS_STRING(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_STRING)
 #define HCL_IS_FPDEC(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_FPDEC)
+
 #define HCL_IS_PROCESS(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_PROCESS)
 #define HCL_IS_SEMAPHORE(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_SEMAPHORE)
 #define HCL_IS_SEMAPHORE_GROUP(hcl,v) (HCL_OOP_IS_POINTER(v) && HCL_OBJ_GET_FLAGS_BRAND(v) == HCL_BRAND_SEMAPHORE_GROUP)
diff --git a/lib/prim.c b/lib/prim.c
index f17cc3d..e42ee59 100644
--- a/lib/prim.c
+++ b/lib/prim.c
@@ -39,9 +39,10 @@ typedef struct pf_t pf_t;
 
 hcl_oop_t hcl_makeprim (hcl_t* hcl, hcl_pfimpl_t primimpl, hcl_oow_t minargs, hcl_oow_t maxargs, hcl_mod_t* mod)
 {
-	hcl_oop_prim_t obj; /* in principle, hcl_oop_word_t with HCL_PRIM_NUM_WORDS elements */
+#if 0
+	hcl_oop_prim_t obj; /* in principle, hcl_oop_word_t with HCL_PRIM_NAMED_INSTVARS elements */
 
-	obj = (hcl_oop_prim_t)hcl_allocwordobj(hcl, HCL_BRAND_PRIM, HCL_NULL, HCL_PRIM_NUM_WORDS);
+	obj = (hcl_oop_prim_t)hcl_allocwordobj(hcl, HCL_BRAND_PRIM, HCL_NULL, HCL_PRIM_NAMED_INSTVARS);
 	if (HCL_LIKELY(obj))
 	{
 		obj->impl = (hcl_oow_t)primimpl;
@@ -51,6 +52,25 @@ hcl_oop_t hcl_makeprim (hcl_t* hcl, hcl_pfimpl_t primimpl, hcl_oow_t minargs, hc
 	}
 
 	return (hcl_oop_t)obj;
+#else
+	hcl_oop_prim_t v; /* in principle, hcl_oop_word_t with HCL_PRIM_NUM_WORDS elements */
+
+	v = (hcl_oop_prim_t)hcl_instantiate(hcl, hcl->c_primitive, HCL_NULL, 0);
+	if (HCL_UNLIKELY(!v))
+	{
+		const hcl_ooch_t* orgmsg = hcl_backuperrmsg(hcl);
+		hcl_seterrbfmt (hcl, HCL_ERRNUM(hcl), "unable to make primitive - %js", orgmsg);
+	}
+	else
+	{
+		v->impl = (hcl_oow_t)primimpl;
+		v->min_nargs = minargs;
+		v->max_nargs = maxargs;
+		v->mod = (hcl_oow_t)mod;
+	}
+
+	return (hcl_oop_t)v;
+#endif
 }
 
 /* ------------------------------------------------------------------------- */