diff --git a/src/libcoreint/opcodes-ecma-arithmetics.c b/src/libcoreint/opcodes-ecma-arithmetics.c
index 63b9079e1..9034fb619 100644
--- a/src/libcoreint/opcodes-ecma-arithmetics.c
+++ b/src/libcoreint/opcodes-ecma-arithmetics.c
@@ -125,8 +125,8 @@ opfunc_addition (opcode_t opdata, /**< operation data */
   ECMA_TRY_CATCH (prim_left_value, ecma_op_to_primitive (left_value.u.value, ECMA_PREFERRED_TYPE_NO), ret_value);
   ECMA_TRY_CATCH (prim_right_value, ecma_op_to_primitive (right_value.u.value, ECMA_PREFERRED_TYPE_NO), ret_value);
 
-  if (prim_left_value.u.value.value_type == ECMA_TYPE_STRING
-      || prim_right_value.u.value.value_type == ECMA_TYPE_STRING)
+  if (ecma_is_value_string (prim_left_value.u.value)
+      || ecma_is_value_string (prim_right_value.u.value))
   {
     ECMA_TRY_CATCH (str_left_value, ecma_op_to_string (prim_left_value.u.value), ret_value);
     ECMA_TRY_CATCH (str_right_value, ecma_op_to_string (prim_right_value.u.value), ret_value);
diff --git a/src/libcoreint/opcodes-ecma-relational.c b/src/libcoreint/opcodes-ecma-relational.c
index a30cdbd8e..72c5b4395 100644
--- a/src/libcoreint/opcodes-ecma-relational.c
+++ b/src/libcoreint/opcodes-ecma-relational.c
@@ -253,7 +253,7 @@ opfunc_instanceof (opcode_t opdata __unused, /**< operation data */
   ECMA_TRY_CATCH (left_value, get_variable_value (int_data, left_var_idx, false), ret_value);
   ECMA_TRY_CATCH (right_value, get_variable_value (int_data, right_var_idx, false), ret_value);
 
-  if (right_value.u.value.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (right_value.u.value))
   {
     ret_value = ecma_make_throw_obj_completion_value (ecma_new_standard_error (ECMA_ERROR_TYPE));
   }
@@ -300,7 +300,7 @@ opfunc_in (opcode_t opdata __unused, /**< operation data */
   ECMA_TRY_CATCH (left_value, get_variable_value (int_data, left_var_idx, false), ret_value);
   ECMA_TRY_CATCH (right_value, get_variable_value (int_data, right_var_idx, false), ret_value);
 
-  if (right_value.u.value.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (right_value.u.value))
   {
     ret_value = ecma_make_throw_obj_completion_value (ecma_new_standard_error (ECMA_ERROR_TYPE));
   }
diff --git a/src/libcoreint/opcodes-helpers-variables.c b/src/libcoreint/opcodes-helpers-variables.c
index 53f240794..085374293 100644
--- a/src/libcoreint/opcodes-helpers-variables.c
+++ b/src/libcoreint/opcodes-helpers-variables.c
@@ -32,7 +32,7 @@ do_strict_eval_arguments_check (ecma_reference_t ref) /**< ECMA-reference */
 
   if (ref.is_strict)
   {
-    if (ref.base.value_type == ECMA_TYPE_OBJECT)
+    if (ecma_is_value_object (ref.base))
     {
       ecma_object_t *obj_p = ECMA_GET_POINTER (ref.base.value);
 
diff --git a/src/libcoreint/opcodes-native-call.c b/src/libcoreint/opcodes-native-call.c
index ddcd1c0d0..9de8d1aca 100644
--- a/src/libcoreint/opcodes-native-call.c
+++ b/src/libcoreint/opcodes-native-call.c
@@ -62,7 +62,7 @@ opfunc_native_call (opcode_t opdata, /**< operation data */
       case OPCODE_NATIVE_CALL_LED_TOGGLE:
       {
         JERRY_ASSERT (args_number == 1);
-        JERRY_ASSERT (arg_values[0].value_type == ECMA_TYPE_NUMBER);
+        JERRY_ASSERT (ecma_is_value_number (arg_values[0]));
         ecma_number_t* num_p = (ecma_number_t*) ECMA_GET_NON_NULL_POINTER (arg_values[0].value);
         uint32_t int_num = ecma_number_to_uint32 (*num_p);
         led_toggle (int_num);
@@ -73,7 +73,7 @@ opfunc_native_call (opcode_t opdata, /**< operation data */
       case OPCODE_NATIVE_CALL_LED_ON:
       {
         JERRY_ASSERT (args_number == 1);
-        JERRY_ASSERT (arg_values[0].value_type == ECMA_TYPE_NUMBER);
+        JERRY_ASSERT (ecma_is_value_number (arg_values[0]));
         ecma_number_t* num_p = (ecma_number_t*) ECMA_GET_NON_NULL_POINTER (arg_values[0].value);
         uint32_t int_num = ecma_number_to_uint32 (*num_p);
         led_on (int_num);
@@ -84,7 +84,7 @@ opfunc_native_call (opcode_t opdata, /**< operation data */
       case OPCODE_NATIVE_CALL_LED_OFF:
       {
         JERRY_ASSERT (args_number == 1);
-        JERRY_ASSERT (arg_values[0].value_type == ECMA_TYPE_NUMBER);
+        JERRY_ASSERT (ecma_is_value_number (arg_values[0]));
         ecma_number_t* num_p = (ecma_number_t*) ECMA_GET_NON_NULL_POINTER (arg_values[0].value);
         uint32_t int_num = ecma_number_to_uint32 (*num_p);
         led_off (int_num);
@@ -95,7 +95,7 @@ opfunc_native_call (opcode_t opdata, /**< operation data */
       case OPCODE_NATIVE_CALL_LED_ONCE:
       {
         JERRY_ASSERT (args_number == 1);
-        JERRY_ASSERT (arg_values[0].value_type == ECMA_TYPE_NUMBER);
+        JERRY_ASSERT (ecma_is_value_number (arg_values[0]));
         ecma_number_t* num_p = (ecma_number_t*) ECMA_GET_NON_NULL_POINTER (arg_values[0].value);
         uint32_t int_num = ecma_number_to_uint32 (*num_p);
         led_blink_once (int_num);
@@ -106,7 +106,7 @@ opfunc_native_call (opcode_t opdata, /**< operation data */
       case OPCODE_NATIVE_CALL_WAIT:
       {
         JERRY_ASSERT (args_number == 1);
-        JERRY_ASSERT (arg_values[0].value_type == ECMA_TYPE_NUMBER);
+        JERRY_ASSERT (ecma_is_value_number (arg_values[0]));
         ecma_number_t* num_p = (ecma_number_t*) ECMA_GET_NON_NULL_POINTER (arg_values[0].value);
         uint32_t int_num = ecma_number_to_uint32 (*num_p);
         wait_ms (int_num);
diff --git a/src/libcoreint/opcodes.c b/src/libcoreint/opcodes.c
index 849db24b6..9b1ab6a2c 100644
--- a/src/libcoreint/opcodes.c
+++ b/src/libcoreint/opcodes.c
@@ -898,7 +898,7 @@ opfunc_obj_decl (opcode_t opdata, /**< operation data */
         }
         else if (type == OPCODE_META_TYPE_VARG_PROP_GETTER)
         {
-          JERRY_ASSERT (value_for_prop_desc.u.value.value_type == ECMA_TYPE_OBJECT);
+          JERRY_ASSERT (ecma_is_value_object (value_for_prop_desc.u.value));
 
           prop_desc.is_get_defined = true;
           prop_desc.get_p = ECMA_GET_NON_NULL_POINTER (value_for_prop_desc.u.value.value);
@@ -911,7 +911,7 @@ opfunc_obj_decl (opcode_t opdata, /**< operation data */
         }
         else
         {
-          JERRY_ASSERT (value_for_prop_desc.u.value.value_type == ECMA_TYPE_OBJECT);
+          JERRY_ASSERT (ecma_is_value_object (value_for_prop_desc.u.value));
 
           prop_desc.is_set_defined = true;
           prop_desc.set_p = ECMA_GET_NON_NULL_POINTER (value_for_prop_desc.u.value.value);
@@ -1466,7 +1466,7 @@ opfunc_delete_var (opcode_t opdata, /**< operation data */
     }
     else
     {
-      JERRY_ASSERT (ref.base.value_type == ECMA_TYPE_OBJECT);
+      JERRY_ASSERT (ecma_is_value_object (ref.base));
       ecma_object_t *bindings_p = ECMA_GET_NON_NULL_POINTER (ref.base.value);
       JERRY_ASSERT (ecma_is_lexical_environment (bindings_p));
 
@@ -1514,7 +1514,7 @@ opfunc_delete_prop (opcode_t opdata, /**< operation data */
   ECMA_TRY_CATCH (check_coercible_ret, ecma_op_check_object_coercible (base_value.u.value), ret_value);
   ECMA_TRY_CATCH (str_name_value, ecma_op_to_string (name_value.u.value), ret_value);
 
-  JERRY_ASSERT (str_name_value.u.value.value_type == ECMA_TYPE_STRING);
+  JERRY_ASSERT (ecma_is_value_string (str_name_value.u.value));
   ecma_string_t *name_string_p = ECMA_GET_NON_NULL_POINTER (str_name_value.u.value.value);
 
   if (ecma_is_value_undefined (base_value.u.value))
@@ -1533,7 +1533,7 @@ opfunc_delete_prop (opcode_t opdata, /**< operation data */
   {
     ECMA_TRY_CATCH (obj_value, ecma_op_to_object (base_value.u.value), ret_value);
 
-    JERRY_ASSERT (obj_value.u.value.value_type == ECMA_TYPE_OBJECT);
+    JERRY_ASSERT (ecma_is_value_object (obj_value.u.value));
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (obj_value.u.value.value);
     JERRY_ASSERT (!ecma_is_lexical_environment (obj_p));
 
diff --git a/src/libecmabuiltins/ecma-builtin-array.c b/src/libecmabuiltins/ecma-builtin-array.c
index c8e8fd45a..31d8e8dad 100644
--- a/src/libecmabuiltins/ecma-builtin-array.c
+++ b/src/libecmabuiltins/ecma-builtin-array.c
@@ -59,7 +59,7 @@ ecma_builtin_array_object_is_array (ecma_value_t this_arg __unused, /**< 'this'
 {
   ecma_simple_value_t is_array = ECMA_SIMPLE_VALUE_FALSE;
 
-  if (arg.value_type == ECMA_TYPE_OBJECT)
+  if (ecma_is_value_object (arg))
   {
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (arg.value);
 
diff --git a/src/libecmabuiltins/ecma-builtin-boolean-prototype.c b/src/libecmabuiltins/ecma-builtin-boolean-prototype.c
index d4e082aa2..445537467 100644
--- a/src/libecmabuiltins/ecma-builtin-boolean-prototype.c
+++ b/src/libecmabuiltins/ecma-builtin-boolean-prototype.c
@@ -98,7 +98,7 @@ ecma_builtin_boolean_prototype_object_value_of (ecma_value_t this) /**< this arg
   {
     return ecma_make_normal_completion_value (this);
   }
-  else if (this.value_type == ECMA_TYPE_OBJECT)
+  else if (ecma_is_value_object (this))
   {
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (this.value);
 
diff --git a/src/libecmabuiltins/ecma-builtin-error-prototype.c b/src/libecmabuiltins/ecma-builtin-error-prototype.c
index 87f5696e3..80db82d24 100644
--- a/src/libecmabuiltins/ecma-builtin-error-prototype.c
+++ b/src/libecmabuiltins/ecma-builtin-error-prototype.c
@@ -59,7 +59,7 @@ ecma_builtin_error_prototype_object_to_string (ecma_value_t this) /**< this argu
   ecma_completion_value_t ret_value;
 
   // 2.
-  if (this.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (this))
   {
     ret_value = ecma_make_throw_obj_completion_value (ecma_new_standard_error (ECMA_ERROR_TYPE));
   }
@@ -116,8 +116,8 @@ ecma_builtin_error_prototype_object_to_string (ecma_value_t this) /**< this argu
       }
       else
       {
-        JERRY_ASSERT (name_to_str_completion.u.value.value_type == ECMA_TYPE_STRING);
-        JERRY_ASSERT (msg_to_str_completion.u.value.value_type == ECMA_TYPE_STRING);
+        JERRY_ASSERT (ecma_is_value_string (name_to_str_completion.u.value));
+        JERRY_ASSERT (ecma_is_value_string (msg_to_str_completion.u.value));
 
         ecma_string_t *name_string_p = ECMA_GET_NON_NULL_POINTER (name_to_str_completion.u.value.value);
         ecma_string_t *msg_string_p = ECMA_GET_NON_NULL_POINTER (msg_to_str_completion.u.value.value);
diff --git a/src/libecmabuiltins/ecma-builtin-number-prototype.c b/src/libecmabuiltins/ecma-builtin-number-prototype.c
index aeebd3837..bc3e22c0d 100644
--- a/src/libecmabuiltins/ecma-builtin-number-prototype.c
+++ b/src/libecmabuiltins/ecma-builtin-number-prototype.c
@@ -60,13 +60,13 @@ ecma_builtin_number_prototype_object_to_string (ecma_value_t this, /**< this arg
 {
   ecma_number_t this_arg_number;
 
-  if (this.value_type == ECMA_TYPE_NUMBER)
+  if (ecma_is_value_number (this))
   {
     ecma_number_t *this_arg_number_p = ECMA_GET_NON_NULL_POINTER (this.value);
 
     this_arg_number = *this_arg_number_p;
   }
-  else if (this.value_type == ECMA_TYPE_OBJECT)
+  else if (ecma_is_value_object (this))
   {
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (this.value);
 
@@ -128,11 +128,11 @@ ecma_builtin_number_prototype_object_to_locale_string (ecma_value_t this) /**< t
 static ecma_completion_value_t
 ecma_builtin_number_prototype_object_value_of (ecma_value_t this) /**< this argument */
 {
-  if (this.value_type == ECMA_TYPE_NUMBER)
+  if (ecma_is_value_number (this))
   {
     return ecma_make_normal_completion_value (ecma_copy_value (this, true));
   }
-  else if (this.value_type == ECMA_TYPE_OBJECT)
+  else if (ecma_is_value_object (this))
   {
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (this.value);
 
diff --git a/src/libecmabuiltins/ecma-builtin-object-prototype.c b/src/libecmabuiltins/ecma-builtin-object-prototype.c
index 786734a3b..83a4cc7ac 100644
--- a/src/libecmabuiltins/ecma-builtin-object-prototype.c
+++ b/src/libecmabuiltins/ecma-builtin-object-prototype.c
@@ -73,7 +73,7 @@ ecma_builtin_object_prototype_object_to_string (ecma_value_t this) /**< this arg
       return obj_this;
     }
 
-    JERRY_ASSERT (obj_this.u.value.value_type == ECMA_TYPE_OBJECT);
+    JERRY_ASSERT (ecma_is_value_object (obj_this.u.value));
 
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (obj_this.u.value.value);
 
diff --git a/src/libecmabuiltins/ecma-builtin-object.c b/src/libecmabuiltins/ecma-builtin-object.c
index fd9e14cc3..f2b4a2afa 100644
--- a/src/libecmabuiltins/ecma-builtin-object.c
+++ b/src/libecmabuiltins/ecma-builtin-object.c
@@ -313,7 +313,7 @@ ecma_builtin_object_object_define_property (ecma_value_t this_arg __unused, /**<
 {
   ecma_completion_value_t ret_value;
 
-  if (arg1.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (arg1))
   {
     ret_value = ecma_make_throw_obj_completion_value (ecma_new_standard_error (ECMA_ERROR_TYPE));
   }
diff --git a/src/libecmabuiltins/ecma-builtin-string-prototype.c b/src/libecmabuiltins/ecma-builtin-string-prototype.c
index 98d063cd7..2dfe37685 100644
--- a/src/libecmabuiltins/ecma-builtin-string-prototype.c
+++ b/src/libecmabuiltins/ecma-builtin-string-prototype.c
@@ -56,11 +56,11 @@
 static ecma_completion_value_t
 ecma_builtin_string_prototype_object_to_string (ecma_value_t this) /**< this argument */
 {
-  if (this.value_type == ECMA_TYPE_STRING)
+  if (ecma_is_value_string (this))
   {
     return ecma_make_normal_completion_value (ecma_copy_value (this, true));
   }
-  else if (this.value_type == ECMA_TYPE_OBJECT)
+  else if (ecma_is_value_object (this))
   {
     ecma_object_t *obj_p = ECMA_GET_NON_NULL_POINTER (this.value);
 
diff --git a/src/libecmabuiltins/ecma-builtin-string.c b/src/libecmabuiltins/ecma-builtin-string.c
index 239088593..e9262e9a7 100644
--- a/src/libecmabuiltins/ecma-builtin-string.c
+++ b/src/libecmabuiltins/ecma-builtin-string.c
@@ -74,7 +74,7 @@ ecma_builtin_string_object_from_char_code (ecma_value_t this_arg __unused, /**<
                     ecma_op_to_number (args[arg_index]),
                     ret_value);
 
-    JERRY_ASSERT (arg_num_value.u.value.value_type == ECMA_TYPE_NUMBER);
+    JERRY_ASSERT (ecma_is_value_number (arg_num_value.u.value));
     ecma_number_t *arg_num_p = ECMA_GET_NON_NULL_POINTER (arg_num_value.u.value.value);
 
     uint32_t uint32_char_code = ecma_number_to_uint32 (*arg_num_p);
diff --git a/src/libecmaobjects/ecma-gc.c b/src/libecmaobjects/ecma-gc.c
index e44784ced..416c65058 100644
--- a/src/libecmaobjects/ecma-gc.c
+++ b/src/libecmaobjects/ecma-gc.c
@@ -238,7 +238,7 @@ void
 ecma_gc_update_may_ref_younger_object_flag_by_value (ecma_object_t *obj_p, /**< object */
                                                      ecma_value_t value) /**< value */
 {
-  if (value.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (value))
   {
     return;
   }
@@ -331,7 +331,7 @@ ecma_gc_mark (ecma_object_t *object_p, /**< start object */
       {
         ecma_value_t value = property_p->u.named_data_property.value;
 
-        if (value.value_type == ECMA_TYPE_OBJECT)
+        if (ecma_is_value_object (value))
         {
           ecma_object_t *value_obj_p = ECMA_GET_NON_NULL_POINTER(value.value);
 
diff --git a/src/libecmaobjects/ecma-helpers-value.c b/src/libecmaobjects/ecma-helpers-value.c
index 3285e9612..71fd6fad4 100644
--- a/src/libecmaobjects/ecma-helpers-value.c
+++ b/src/libecmaobjects/ecma-helpers-value.c
@@ -92,6 +92,42 @@ ecma_is_value_true (ecma_value_t value) /**< ecma-value */
   return (value.value_type == ECMA_TYPE_SIMPLE && value.value == ECMA_SIMPLE_VALUE_TRUE);
 } /* ecma_is_value_true */
 
+/**
+ * Check if the value is ecma-number.
+ *
+ * @return true - if the value contains ecma-number value,
+ *         false - otherwise.
+ */
+bool
+ecma_is_value_number (ecma_value_t value) /**< ecma-value */
+{
+  return (value.value_type == ECMA_TYPE_NUMBER);
+} /* ecma_is_value_number */
+
+/**
+ * Check if the value is ecma-string.
+ *
+ * @return true - if the value contains ecma-string value,
+ *         false - otherwise.
+ */
+bool
+ecma_is_value_string (ecma_value_t value) /**< ecma-value */
+{
+  return (value.value_type == ECMA_TYPE_STRING);
+} /* ecma_is_value_string */
+
+/**
+ * Check if the value is object.
+ *
+ * @return true - if the value contains object value,
+ *         false - otherwise.
+ */
+bool
+ecma_is_value_object (ecma_value_t value) /**< ecma-value */
+{
+  return (value.value_type == ECMA_TYPE_OBJECT);
+} /* ecma_is_value_object */
+
 /**
  * Simple value constructor
  */
diff --git a/src/libecmaobjects/ecma-helpers.h b/src/libecmaobjects/ecma-helpers.h
index 68dcab5f7..464381b32 100644
--- a/src/libecmaobjects/ecma-helpers.h
+++ b/src/libecmaobjects/ecma-helpers.h
@@ -67,6 +67,10 @@ extern bool ecma_is_value_null (ecma_value_t value);
 extern bool ecma_is_value_boolean (ecma_value_t value);
 extern bool ecma_is_value_true (ecma_value_t value);
 
+extern bool ecma_is_value_number (ecma_value_t value);
+extern bool ecma_is_value_string (ecma_value_t value);
+extern bool ecma_is_value_object (ecma_value_t value);
+
 extern ecma_value_t ecma_make_simple_value (ecma_simple_value_t value);
 extern ecma_value_t ecma_make_number_value (ecma_number_t* num_p);
 extern ecma_value_t ecma_make_string_value (ecma_string_t* ecma_string_p);
diff --git a/src/libecmaoperations/ecma-array-object.c b/src/libecmaoperations/ecma-array-object.c
index d1f803da9..e978f2f4b 100644
--- a/src/libecmaoperations/ecma-array-object.c
+++ b/src/libecmaoperations/ecma-array-object.c
@@ -79,7 +79,7 @@ ecma_op_create_array_object (ecma_value_t *arguments_list_p, /**< list of argume
 
   if (is_treat_single_arg_as_length
       && arguments_list_len == 1
-      && arguments_list_p[0].value_type == ECMA_TYPE_NUMBER)
+      && ecma_is_value_number (arguments_list_p[0]))
   {
     ecma_number_t *num_p = ECMA_GET_NON_NULL_POINTER (arguments_list_p[0].value);
     uint32_t num_uint32 = ecma_number_to_uint32 (*num_p);
@@ -185,7 +185,7 @@ ecma_op_array_object_define_own_property (ecma_object_t *obj_p, /**< the array o
   // 2.
   ecma_value_t old_len_value = len_prop_p->u.named_data_property.value;
 
-  JERRY_ASSERT (old_len_value.value_type == ECMA_TYPE_NUMBER);
+  JERRY_ASSERT (ecma_is_value_number (old_len_value));
 
   ecma_number_t *num_p = ECMA_GET_NON_NULL_POINTER (old_len_value.value);
   uint32_t old_len_uint32 = ecma_number_to_uint32 (*num_p);
@@ -215,7 +215,7 @@ ecma_op_array_object_define_own_property (ecma_object_t *obj_p, /**< the array o
     }
 
     JERRY_ASSERT (ecma_is_completion_value_normal (completion)
-                  && completion.u.value.value_type == ECMA_TYPE_NUMBER);
+                  && ecma_is_value_number (completion.u.value));
 
     new_len_num = *(ecma_number_t*) ECMA_GET_NON_NULL_POINTER (completion.u.value.value);
 
@@ -315,7 +315,7 @@ ecma_op_array_object_define_own_property (ecma_object_t *obj_p, /**< the array o
               // iii
               if (ecma_is_completion_value_normal_false (delete_succeeded))
               {
-                JERRY_ASSERT (new_len_property_desc.value.value_type == ECMA_TYPE_NUMBER);
+                JERRY_ASSERT (ecma_is_value_number (new_len_property_desc.value));
 
                 ecma_number_t *new_len_num_p = ECMA_GET_NON_NULL_POINTER (new_len_property_desc.value.value);
 
diff --git a/src/libecmaoperations/ecma-comparison.c b/src/libecmaoperations/ecma-comparison.c
index 627fc452f..e32aa8e53 100644
--- a/src/libecmaoperations/ecma-comparison.c
+++ b/src/libecmaoperations/ecma-comparison.c
@@ -41,16 +41,16 @@ ecma_op_abstract_equality_compare (ecma_value_t x, /**< first operand */
   const bool is_x_undefined = ecma_is_value_undefined (x);
   const bool is_x_null = ecma_is_value_null (x);
   const bool is_x_boolean = ecma_is_value_boolean (x);
-  const bool is_x_number = (x.value_type == ECMA_TYPE_NUMBER);
-  const bool is_x_string = (x.value_type == ECMA_TYPE_STRING);
-  const bool is_x_object = (x.value_type == ECMA_TYPE_OBJECT);
+  const bool is_x_number = ecma_is_value_number (x);
+  const bool is_x_string = ecma_is_value_string (x);
+  const bool is_x_object = ecma_is_value_object (x);
 
   const bool is_y_undefined = ecma_is_value_undefined (y);
   const bool is_y_null = ecma_is_value_null (y);
   const bool is_y_boolean = ecma_is_value_boolean (y);
-  const bool is_y_number = (y.value_type == ECMA_TYPE_NUMBER);
-  const bool is_y_string = (y.value_type == ECMA_TYPE_STRING);
-  const bool is_y_object = (y.value_type == ECMA_TYPE_OBJECT);
+  const bool is_y_number = ecma_is_value_number (y);
+  const bool is_y_string = ecma_is_value_string (y);
+  const bool is_y_object = ecma_is_value_object (y);
 
   const bool is_types_equal = ((is_x_undefined && is_y_undefined)
                                || (is_x_null && is_y_null)
@@ -222,16 +222,16 @@ ecma_op_strict_equality_compare (ecma_value_t x, /**< first operand */
   const bool is_x_undefined = ecma_is_value_undefined (x);
   const bool is_x_null = ecma_is_value_null (x);
   const bool is_x_boolean = ecma_is_value_boolean (x);
-  const bool is_x_number = (x.value_type == ECMA_TYPE_NUMBER);
-  const bool is_x_string = (x.value_type == ECMA_TYPE_STRING);
-  const bool is_x_object = (x.value_type == ECMA_TYPE_OBJECT);
+  const bool is_x_number = ecma_is_value_number (x);
+  const bool is_x_string = ecma_is_value_string (x);
+  const bool is_x_object = ecma_is_value_object (x);
 
   const bool is_y_undefined = ecma_is_value_undefined (y);
   const bool is_y_null = ecma_is_value_null (y);
   const bool is_y_boolean = ecma_is_value_boolean (y);
-  const bool is_y_number = (y.value_type == ECMA_TYPE_NUMBER);
-  const bool is_y_string = (y.value_type == ECMA_TYPE_STRING);
-  const bool is_y_object = (y.value_type == ECMA_TYPE_OBJECT);
+  const bool is_y_number = ecma_is_value_number (y);
+  const bool is_y_string = ecma_is_value_string (y);
+  const bool is_y_object = ecma_is_value_object (y);
 
   const bool is_types_equal = ((is_x_undefined && is_y_undefined)
                                || (is_x_null && is_y_null)
@@ -338,8 +338,8 @@ ecma_op_abstract_relational_compare (ecma_value_t x, /**< first operand */
   px = left_first ? prim_first_converted_value : prim_second_converted_value;
   py = left_first ? prim_second_converted_value : prim_first_converted_value;
 
-  const bool is_px_string = (px.u.value.value_type == ECMA_TYPE_STRING);
-  const bool is_py_string = (py.u.value.value_type == ECMA_TYPE_STRING);
+  const bool is_px_string = ecma_is_value_string (px.u.value);
+  const bool is_py_string = ecma_is_value_string (py.u.value);
 
   if (!(is_px_string && is_py_string))
   {
diff --git a/src/libecmaoperations/ecma-conversion.c b/src/libecmaoperations/ecma-conversion.c
index 579c31d50..75785708b 100644
--- a/src/libecmaoperations/ecma-conversion.c
+++ b/src/libecmaoperations/ecma-conversion.c
@@ -99,16 +99,16 @@ ecma_op_same_value (ecma_value_t x, /**< ecma-value */
   const bool is_x_undefined = ecma_is_value_undefined (x);
   const bool is_x_null = ecma_is_value_null (x);
   const bool is_x_boolean = ecma_is_value_boolean (x);
-  const bool is_x_number = (x.value_type == ECMA_TYPE_NUMBER);
-  const bool is_x_string = (x.value_type == ECMA_TYPE_STRING);
-  const bool is_x_object = (x.value_type == ECMA_TYPE_OBJECT);
+  const bool is_x_number = ecma_is_value_number (x);
+  const bool is_x_string = ecma_is_value_string (x);
+  const bool is_x_object = ecma_is_value_object (x);
 
   const bool is_y_undefined = ecma_is_value_undefined (y);
   const bool is_y_null = ecma_is_value_null (y);
   const bool is_y_boolean = ecma_is_value_boolean (y);
-  const bool is_y_number = (y.value_type == ECMA_TYPE_NUMBER);
-  const bool is_y_string = (y.value_type == ECMA_TYPE_STRING);
-  const bool is_y_object = (y.value_type == ECMA_TYPE_OBJECT);
+  const bool is_y_number = ecma_is_value_number (y);
+  const bool is_y_string = ecma_is_value_string (y);
+  const bool is_y_object = ecma_is_value_object (y);
 
   const bool is_types_equal = ((is_x_undefined && is_y_undefined)
                                || (is_x_null && is_y_null)
@@ -361,7 +361,7 @@ ecma_op_to_number (ecma_value_t value) /**< ecma-value */
 ecma_completion_value_t
 ecma_op_to_string (ecma_value_t value) /**< ecma-value */
 {
-  if (unlikely (value.value_type == ECMA_TYPE_OBJECT))
+  if (unlikely (ecma_is_value_object (value)))
   {
     ecma_completion_value_t ret_value;
 
@@ -643,7 +643,7 @@ ecma_op_to_property_descriptor (ecma_value_t obj_value, /**< object value */
   ecma_completion_value_t ret_value = ecma_make_empty_completion_value ();
 
   // 1.
-  if (obj_value.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (obj_value))
   {
     ret_value = ecma_make_throw_obj_completion_value (ecma_new_standard_error (ECMA_ERROR_TYPE));
   }
@@ -804,7 +804,7 @@ ecma_op_to_property_descriptor (ecma_value_t obj_value, /**< object value */
           }
           else
           {
-            JERRY_ASSERT (get_prop_value.u.value.value_type == ECMA_TYPE_OBJECT);
+            JERRY_ASSERT (ecma_is_value_object (get_prop_value.u.value));
 
             ecma_object_t *get_p = ECMA_GET_NON_NULL_POINTER (get_prop_value.u.value.value);
             ecma_ref_object (get_p);
@@ -848,7 +848,7 @@ ecma_op_to_property_descriptor (ecma_value_t obj_value, /**< object value */
           }
           else
           {
-            JERRY_ASSERT (set_prop_value.u.value.value_type == ECMA_TYPE_OBJECT);
+            JERRY_ASSERT (ecma_is_value_object (set_prop_value.u.value));
 
             ecma_object_t *set_p = ECMA_GET_NON_NULL_POINTER (set_prop_value.u.value.value);
             ecma_ref_object (set_p);
diff --git a/src/libecmaoperations/ecma-function-object.c b/src/libecmaoperations/ecma-function-object.c
index 170b6b5e7..b7ea0c061 100644
--- a/src/libecmaoperations/ecma-function-object.c
+++ b/src/libecmaoperations/ecma-function-object.c
@@ -89,7 +89,7 @@ ecma_unpack_code_internal_property_value (uint32_t value, /**< packed value */
 bool
 ecma_op_is_callable (ecma_value_t value) /**< ecma-value */
 {
-  if (value.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (value))
   {
     return false;
   }
@@ -113,7 +113,7 @@ ecma_op_is_callable (ecma_value_t value) /**< ecma-value */
 bool
 ecma_is_constructor (ecma_value_t value) /**< ecma-value */
 {
-  if (value.value_type != ECMA_TYPE_OBJECT)
+  if (!ecma_is_value_object (value))
   {
     return false;
   }
@@ -338,7 +338,7 @@ ecma_function_call_setup_args_variables (ecma_object_t *func_obj_p, /**< Functio
     JERRY_ASSERT (is_moved);
 
     ecma_value_t formal_parameter_name_value = *formal_params_iterator.current_value_p;
-    JERRY_ASSERT (formal_parameter_name_value.value_type == ECMA_TYPE_STRING);
+    JERRY_ASSERT (ecma_is_value_string (formal_parameter_name_value));
     ecma_string_t *formal_parameter_name_string_p = ECMA_GET_NON_NULL_POINTER (formal_parameter_name_value.value);
     
     bool arg_already_declared = ecma_op_has_binding (env_p, formal_parameter_name_string_p);
@@ -390,7 +390,7 @@ ecma_op_function_has_instance (ecma_object_t *func_obj_p, /**< Function object *
 
   if (ecma_get_object_type (func_obj_p) == ECMA_OBJECT_TYPE_FUNCTION)
   {
-    if (value.value_type != ECMA_TYPE_OBJECT)
+    if (!ecma_is_value_object (value))
     {
       return ecma_make_simple_completion_value (ECMA_SIMPLE_VALUE_FALSE);
     }
@@ -406,7 +406,7 @@ ecma_op_function_has_instance (ecma_object_t *func_obj_p, /**< Function object *
                     ecma_op_object_get (func_obj_p, prototype_magic_string_p),
                     ret_value);
 
-    if (prototype_obj_value.u.value.value_type != ECMA_TYPE_OBJECT)
+    if (!ecma_is_value_object (prototype_obj_value.u.value))
     {
       ret_value = ecma_make_throw_obj_completion_value (ecma_new_standard_error (ECMA_ERROR_TYPE));
     }
@@ -597,7 +597,7 @@ ecma_op_function_construct (ecma_object_t *func_obj_p, /**< Function object */
 
     //  6.
     ecma_object_t *prototype_p;
-    if (func_obj_prototype_prop_value.u.value.value_type == ECMA_TYPE_OBJECT)
+    if (ecma_is_value_object (func_obj_prototype_prop_value.u.value))
     {
       prototype_p = ECMA_GET_NON_NULL_POINTER (func_obj_prototype_prop_value.u.value.value);
       ecma_ref_object (prototype_p);
@@ -628,7 +628,7 @@ ecma_op_function_construct (ecma_object_t *func_obj_p, /**< Function object */
     ecma_value_t obj_value;
 
     // 9.
-    if (call_completion.u.value.value_type == ECMA_TYPE_OBJECT)
+    if (ecma_is_value_object (call_completion.u.value))
     {
       ecma_deref_object (obj_p);
 
diff --git a/src/libecmaoperations/ecma-get-put-value.c b/src/libecmaoperations/ecma-get-put-value.c
index 4c6d12068..ef9a016a5 100644
--- a/src/libecmaoperations/ecma-get-put-value.c
+++ b/src/libecmaoperations/ecma-get-put-value.c
@@ -80,9 +80,9 @@ ecma_op_get_value_object_base (ecma_reference_t ref) /**< ECMA-reference */
   const ecma_value_t base = ref.base;
   const bool is_unresolvable_reference = ecma_is_value_undefined (base);
   const bool has_primitive_base = (ecma_is_value_boolean (base)
-                                   || base.value_type == ECMA_TYPE_NUMBER
-                                   || base.value_type == ECMA_TYPE_STRING);
-  const bool has_object_base = (base.value_type == ECMA_TYPE_OBJECT
+                                   || ecma_is_value_number (base)
+                                   || ecma_is_value_string (base));
+  const bool has_object_base = (ecma_is_value_object (base)
                                 && !(ecma_is_lexical_environment (ECMA_GET_NON_NULL_POINTER(base.value))));
   const bool is_property_reference = has_primitive_base || has_object_base;
 
@@ -207,9 +207,9 @@ ecma_op_put_value_object_base (ecma_reference_t ref, /**< ECMA-reference */
   const ecma_value_t base = ref.base;
   const bool is_unresolvable_reference = ecma_is_value_undefined (base);
   const bool has_primitive_base = (ecma_is_value_boolean (base)
-                                   || base.value_type == ECMA_TYPE_NUMBER
-                                   || base.value_type == ECMA_TYPE_STRING);
-  const bool has_object_base = (base.value_type == ECMA_TYPE_OBJECT
+                                   || ecma_is_value_number (base)
+                                   || ecma_is_value_string (base));
+  const bool has_object_base = (ecma_is_value_object (base)
                                 && !(ecma_is_lexical_environment (ECMA_GET_NON_NULL_POINTER(base.value))));
   const bool is_property_reference = has_primitive_base || has_object_base;
 
diff --git a/src/libecmaoperations/ecma-lex-env.c b/src/libecmaoperations/ecma-lex-env.c
index d9f48d244..bcce4be0d 100644
--- a/src/libecmaoperations/ecma-lex-env.c
+++ b/src/libecmaoperations/ecma-lex-env.c
@@ -467,8 +467,7 @@ ecma_op_create_immutable_binding (ecma_object_t *lex_env_p, /**< lexical environ
 
       JERRY_ASSERT(ecma_is_value_undefined (prop_p->u.named_data_property.value));
 
-      prop_p->u.named_data_property.value.value_type = ECMA_TYPE_SIMPLE;
-      prop_p->u.named_data_property.value.value = ECMA_SIMPLE_VALUE_EMPTY;
+      prop_p->u.named_data_property.value = ecma_make_simple_value (ECMA_SIMPLE_VALUE_EMPTY);
 
       return;
     }
diff --git a/src/libecmaoperations/ecma-objects-arguments.c b/src/libecmaoperations/ecma-objects-arguments.c
index 7c90132c0..2bc3f2ce8 100644
--- a/src/libecmaoperations/ecma-objects-arguments.c
+++ b/src/libecmaoperations/ecma-objects-arguments.c
@@ -140,7 +140,7 @@ ecma_create_arguments_object (ecma_object_t *func_obj_p, /**< callee function */
       JERRY_ASSERT (formal_params_iter_p->current_value_p != NULL);
       JERRY_ASSERT (param_index < formal_params_number);
 
-      JERRY_ASSERT (formal_params_iter_p->current_value_p->value_type == ECMA_TYPE_STRING);
+      JERRY_ASSERT (ecma_is_value_string (*formal_params_iter_p->current_value_p));
       formal_params[param_index] = ECMA_GET_NON_NULL_POINTER (formal_params_iter_p->current_value_p->value);
     }
 
@@ -283,7 +283,7 @@ ecma_arguments_get_mapped_arg_value (ecma_object_t *map_p, /**< [[ParametersMap]
 
   ecma_value_t arg_name_prop_value = arg_name_prop_p->u.named_data_property.value;
 
-  JERRY_ASSERT (arg_name_prop_value.value_type == ECMA_TYPE_STRING);
+  JERRY_ASSERT (ecma_is_value_string (arg_name_prop_value));
   ecma_string_t *arg_name_p = ECMA_GET_NON_NULL_POINTER (arg_name_prop_value.value);
 
   ecma_completion_value_t completion = ecma_op_get_binding_value (lex_env_p,
diff --git a/src/libecmaoperations/ecma-objects-general.c b/src/libecmaoperations/ecma-objects-general.c
index 78705db10..f17887131 100644
--- a/src/libecmaoperations/ecma-objects-general.c
+++ b/src/libecmaoperations/ecma-objects-general.c
@@ -621,7 +621,7 @@ ecma_op_general_object_default_value (ecma_object_t *obj_p, /**< the object */
     }
 
     if (!ecma_is_completion_value_empty (call_completion)
-        && call_completion.u.value.value_type != ECMA_TYPE_OBJECT)
+        && !ecma_is_value_object (call_completion.u.value))
     {
       return call_completion;
     }
diff --git a/src/libecmaoperations/ecma-string-object.c b/src/libecmaoperations/ecma-string-object.c
index 84d2511ab..d492a00cc 100644
--- a/src/libecmaoperations/ecma-string-object.c
+++ b/src/libecmaoperations/ecma-string-object.c
@@ -67,7 +67,7 @@ ecma_op_create_string_object (ecma_value_t *arguments_list_p, /**< list of argum
     {
       JERRY_ASSERT (ecma_is_completion_value_normal (to_str_arg_value));
 
-      JERRY_ASSERT (to_str_arg_value.u.value.value_type == ECMA_TYPE_STRING);
+      JERRY_ASSERT (ecma_is_value_string (to_str_arg_value.u.value));
       prim_prop_str_value_p = ECMA_GET_NON_NULL_POINTER (to_str_arg_value.u.value.value);
 
       int32_t string_len = ecma_string_get_length (prim_prop_str_value_p);