diff --git a/src/globals.h b/src/globals.h
index cdaa2ed06..af8d0ab83 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -34,6 +34,12 @@ typedef signed long ssize_t;
 #define __packed __attribute__((packed))
 #define __noreturn __attribute__((noreturn))
 #define __noinline __attribute__((noinline))
+#ifndef __attribute_const__
+# define __attribute_const__ __attribute__((const))
+#endif /* !__attribute_const__ */
+#ifndef __attribute_pure__
+# define __attribute_pure__ __attribute__((pure))
+#endif /* !__attribute_pure__ */
 
 /**
  * Constants
diff --git a/src/libecmaobjects/ecma-helpers.c b/src/libecmaobjects/ecma-helpers.c
index 5d78393ff..1f1e42042 100644
--- a/src/libecmaobjects/ecma-helpers.c
+++ b/src/libecmaobjects/ecma-helpers.c
@@ -170,8 +170,8 @@ ecma_create_object_lex_env (ecma_object_t *outer_lexical_environment_p, /**< out
 /**
  * Check if the object is lexical environment.
  */
-bool
-ecma_is_lexical_environment (ecma_object_t *object_p) /**< object or lexical environment */
+bool __attribute_pure__
+ecma_is_lexical_environment (const ecma_object_t *object_p) /**< object or lexical environment */
 {
   JERRY_ASSERT (object_p != NULL);
 
@@ -183,8 +183,8 @@ ecma_is_lexical_environment (ecma_object_t *object_p) /**< object or lexical env
 /**
  * Get value of [[Extensible]] object's internal property.
  */
-bool
-ecma_get_object_extensible (ecma_object_t *object_p) /**< object */
+bool __attribute_pure__
+ecma_get_object_extensible (const ecma_object_t *object_p) /**< object */
 {
   JERRY_ASSERT (object_p != NULL);
   JERRY_ASSERT (!ecma_is_lexical_environment (object_p));
@@ -213,8 +213,8 @@ ecma_set_object_extensible (ecma_object_t *object_p, /**< object */
 /**
  * Get object's internal implementation-defined type.
  */
-ecma_object_type_t
-ecma_get_object_type (ecma_object_t *object_p) /**< object */
+ecma_object_type_t __attribute_pure__
+ecma_get_object_type (const ecma_object_t *object_p) /**< object */
 {
   JERRY_ASSERT (object_p != NULL);
   JERRY_ASSERT (!ecma_is_lexical_environment (object_p));
@@ -243,8 +243,8 @@ ecma_set_object_type (ecma_object_t *object_p, /**< object */
 /**
  * Get object's prototype.
  */
-ecma_object_t*
-ecma_get_object_prototype (ecma_object_t *object_p) /**< object */
+ecma_object_t* __attribute_pure__
+ecma_get_object_prototype (const ecma_object_t *object_p) /**< object */
 {
   JERRY_ASSERT (object_p != NULL);
   JERRY_ASSERT (!ecma_is_lexical_environment (object_p));
@@ -261,8 +261,8 @@ ecma_get_object_prototype (ecma_object_t *object_p) /**< object */
  *
  * @return true / false
  */
-bool
-ecma_get_object_is_builtin (ecma_object_t *object_p) /**< object */
+bool __attribute_pure__
+ecma_get_object_is_builtin (const ecma_object_t *object_p) /**< object */
 {
   JERRY_ASSERT (object_p != NULL);
   JERRY_ASSERT (!ecma_is_lexical_environment (object_p));
@@ -301,8 +301,8 @@ ecma_set_object_is_builtin (ecma_object_t *object_p, /**< object */
 /**
  * Get type of lexical environment.
  */
-ecma_lexical_environment_type_t
-ecma_get_lex_env_type (ecma_object_t *object_p) /**< lexical environment */
+ecma_lexical_environment_type_t __attribute_pure__
+ecma_get_lex_env_type (const ecma_object_t *object_p) /**< lexical environment */
 {
   JERRY_ASSERT (object_p != NULL);
   JERRY_ASSERT (ecma_is_lexical_environment (object_p));
@@ -315,8 +315,8 @@ ecma_get_lex_env_type (ecma_object_t *object_p) /**< lexical environment */
 /**
  * Get outer reference of lexical environment.
  */
-ecma_object_t*
-ecma_get_lex_env_outer_reference (ecma_object_t *object_p) /**< lexical environment */
+ecma_object_t* __attribute_pure__
+ecma_get_lex_env_outer_reference (const ecma_object_t *object_p) /**< lexical environment */
 {
   JERRY_ASSERT (object_p != NULL);
   JERRY_ASSERT (ecma_is_lexical_environment (object_p));
@@ -331,8 +331,8 @@ ecma_get_lex_env_outer_reference (ecma_object_t *object_p) /**< lexical environm
 /**
  * Get object's/lexical environment's property list.
  */
-ecma_property_t*
-ecma_get_property_list (ecma_object_t *object_p) /**< object or lexical environment */
+ecma_property_t* __attribute_pure__
+ecma_get_property_list (const ecma_object_t *object_p) /**< object or lexical environment */
 {
   JERRY_ASSERT (object_p != NULL);
 
diff --git a/src/libecmaobjects/ecma-helpers.h b/src/libecmaobjects/ecma-helpers.h
index 4d28c04b9..2bb1483df 100644
--- a/src/libecmaobjects/ecma-helpers.h
+++ b/src/libecmaobjects/ecma-helpers.h
@@ -197,18 +197,18 @@ extern ecma_object_t* ecma_create_decl_lex_env (ecma_object_t *outer_lexical_env
 extern ecma_object_t* ecma_create_object_lex_env (ecma_object_t *outer_lexical_environment_p,
                                                   ecma_object_t *binding_obj_p,
                                                   bool provide_this);
-extern bool ecma_is_lexical_environment (ecma_object_t *object_p);
-extern bool ecma_get_object_extensible (ecma_object_t *object_p);
+extern bool __attribute_pure__ ecma_is_lexical_environment (const ecma_object_t *object_p);
+extern bool __attribute_pure__ ecma_get_object_extensible (const ecma_object_t *object_p);
 extern void ecma_set_object_extensible (ecma_object_t *object_p, bool is_extensible);
-extern ecma_object_type_t ecma_get_object_type (ecma_object_t *object_p);
+extern ecma_object_type_t __attribute_pure__ ecma_get_object_type (const ecma_object_t *object_p);
 extern void ecma_set_object_type (ecma_object_t *object_p, ecma_object_type_t type);
-extern ecma_object_t* ecma_get_object_prototype (ecma_object_t *object_p);
-extern bool ecma_get_object_is_builtin (ecma_object_t *object_p);
+extern ecma_object_t* __attribute_pure__ ecma_get_object_prototype (const ecma_object_t *object_p);
+extern bool __attribute_pure__ ecma_get_object_is_builtin (const ecma_object_t *object_p);
 extern void ecma_set_object_is_builtin (ecma_object_t *object_p,
                                         bool is_builtin);
-extern ecma_lexical_environment_type_t ecma_get_lex_env_type (ecma_object_t *object_p);
-extern ecma_object_t *ecma_get_lex_env_outer_reference (ecma_object_t *object_p);
-extern ecma_property_t *ecma_get_property_list (ecma_object_t *object_p);
+extern ecma_lexical_environment_type_t __attribute_pure__ ecma_get_lex_env_type (const ecma_object_t *object_p);
+extern ecma_object_t* __attribute_pure__ ecma_get_lex_env_outer_reference (const ecma_object_t *object_p);
+extern ecma_property_t* __attribute_pure__ ecma_get_property_list (const ecma_object_t *object_p);
 
 extern ecma_property_t* ecma_create_internal_property (ecma_object_t *object_p,
                                                        ecma_internal_property_id_t property_id);
diff --git a/src/libruntime/jrt-bit-fields.c b/src/libruntime/jrt-bit-fields.c
index 9cacf2d81..7ae4d2079 100644
--- a/src/libruntime/jrt-bit-fields.c
+++ b/src/libruntime/jrt-bit-fields.c
@@ -21,7 +21,7 @@
  *
  * @return bit-field's value
  */
-extern uint64_t
+uint64_t __attribute_const__
 jrt_extract_bit_field (uint64_t container, /**< container to extract bit-field from */
                        uint32_t lsb, /**< least significant bit of the value
                                       *   to be extracted */
@@ -42,7 +42,7 @@ jrt_extract_bit_field (uint64_t container, /**< container to extract bit-field f
  *
  * @return bit-field's value
  */
-extern uint64_t
+uint64_t __attribute_const__
 jrt_set_bit_field_value (uint64_t container, /**< container to insert bit-field to */
                          uint64_t new_bit_field_value, /**< value of bit-field to insert */
                          uint32_t lsb, /**< least significant bit of the value
diff --git a/src/libruntime/jrt-bit-fields.h b/src/libruntime/jrt-bit-fields.h
index 34112409b..1a8925a4c 100644
--- a/src/libruntime/jrt-bit-fields.h
+++ b/src/libruntime/jrt-bit-fields.h
@@ -16,9 +16,9 @@
 #ifndef JERRY_BIT_FIELDS_H
 #define JERRY_BIT_FIELDS_H
 
-extern uint64_t jrt_extract_bit_field (uint64_t value, uint32_t lsb,
-                                       uint32_t width);
-extern uint64_t jrt_set_bit_field_value (uint64_t value, uint64_t bit_field_value,
-                                         uint32_t lsb, uint32_t width);
+extern uint64_t __attribute_const__ jrt_extract_bit_field (uint64_t value, uint32_t lsb,
+                                                           uint32_t width);
+extern uint64_t __attribute_const__ jrt_set_bit_field_value (uint64_t value, uint64_t bit_field_value,
+                                                             uint32_t lsb, uint32_t width);
 
 #endif /* !JERRY_BIT_FIELDS_H */