diff --git a/desmume/src/libretro-common/file/file_path.c b/desmume/src/libretro-common/file/file_path.c
index f5814d307..f6d043d05 100644
--- a/desmume/src/libretro-common/file/file_path.c
+++ b/desmume/src/libretro-common/file/file_path.c
@@ -20,6 +20,8 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#define _XOPEN_SOURCE 500   /* For strdup, realpath */
+
 #include <stdlib.h>
 #include <boolean.h>
 #include <string.h>