diff --git a/jerry-core/ecma/base/ecma-helpers-number.c b/jerry-core/ecma/base/ecma-helpers-number.c
index d6c2d87d3..f905c3c08 100644
--- a/jerry-core/ecma/base/ecma-helpers-number.c
+++ b/jerry-core/ecma/base/ecma-helpers-number.c
@@ -240,7 +240,7 @@ ecma_number_get_sign_field (ecma_number_t num) /**< ecma-number */
                   fraction is filled with anything but not all zero bits,
  *         false - otherwise
  */
-inline bool JERRY_ATTR_ALWAYS_INLINE
+extern inline bool JERRY_ATTR_ALWAYS_INLINE
 ecma_number_is_nan (ecma_number_t num) /**< ecma-number */
 {
   bool is_nan = (num != num);
diff --git a/jerry-core/ecma/base/ecma-helpers-value.c b/jerry-core/ecma/base/ecma-helpers-value.c
index fde5ec11d..9c91e5408 100644
--- a/jerry-core/ecma/base/ecma-helpers-value.c
+++ b/jerry-core/ecma/base/ecma-helpers-value.c
@@ -305,7 +305,7 @@ JERRY_STATIC_ASSERT ((ECMA_TYPE_STRING | 0x4) == ECMA_TYPE_DIRECT_STRING,
  * @return true - if the value contains ecma-string value,
  *         false - otherwise
  */
-inline bool JERRY_ATTR_CONST JERRY_ATTR_ALWAYS_INLINE
+extern inline bool JERRY_ATTR_CONST JERRY_ATTR_ALWAYS_INLINE
 ecma_is_value_string (ecma_value_t value) /**< ecma value */
 {
   return ((value & (ECMA_VALUE_TYPE_MASK - 0x4)) == ECMA_TYPE_STRING);
diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-helpers-date.c b/jerry-core/ecma/builtin-objects/ecma-builtin-helpers-date.c
index 581725035..08c34016d 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-helpers-date.c
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-helpers-date.c
@@ -41,7 +41,7 @@
  *
  * @return time value for day number
  */
-inline ecma_number_t JERRY_ATTR_ALWAYS_INLINE
+extern inline ecma_number_t JERRY_ATTR_ALWAYS_INLINE
 ecma_date_day (ecma_number_t time) /**< time value */
 {
   JERRY_ASSERT (!ecma_number_is_nan (time));