extern "C" used in skeletons

diff --git a/skeletons/constr_SEQUENCE_OF.h b/skeletons/constr_SEQUENCE_OF.h
index 684ec26..94b04cd 100644
--- a/skeletons/constr_SEQUENCE_OF.h
+++ b/skeletons/constr_SEQUENCE_OF.h
@@ -8,6 +8,10 @@
 #include <asn_application.h>
 #include <constr_SET_OF.h>		/* Implemented using SET OF */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /*
  * A set specialized functions dealing with the SEQUENCE OF type.
  * Generally implemented using SET OF.
@@ -20,4 +24,8 @@
 der_type_encoder_f SEQUENCE_OF_encode_der;
 xer_type_encoder_f SEQUENCE_OF_encode_xer;
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif	/* _CONSTR_SET_OF_H_ */