diff --git a/libs/sofia-sip/libsofia-sip-ua/su/su_uniqueid.c b/libs/sofia-sip/libsofia-sip-ua/su/su_uniqueid.c
index 7d3591c26b..ed278f3121 100644
--- a/libs/sofia-sip/libsofia-sip-ua/su/su_uniqueid.c
+++ b/libs/sofia-sip/libsofia-sip-ua/su/su_uniqueid.c
@@ -84,7 +84,11 @@ union state {
 
 #include <pthread.h>
 
+#if defined(__sun)
+static pthread_once_t once = { PTHREAD_ONCE_INIT };
+#else
 static pthread_once_t once = PTHREAD_ONCE_INIT;
+#endif
 static int done_once = 1;
 static pthread_key_t state_key;