diff --git a/configure.ac b/configure.ac
index de1ac788..013d5185 100644
--- a/configure.ac
+++ b/configure.ac
@@ -236,6 +236,8 @@ case "$host_os" in
 				   [Compiling for Solaris platform])
 		AC_DEFINE_UNQUOTED([TS_CLASS], [1],
 				   [Prevent being scheduled RR])
+		AC_DEFINE_UNQUOTED([_SEM_SEMUN_UNDEFINED], [1],
+				   [The semun structure is undefined])
 		OS_CFLAGS=""
 		OS_CPPFLAGS="-D_REENTRANT"
 		OS_LDFLAGS=""
diff --git a/exec/coroipcs.c b/exec/coroipcs.c
index d960b9ef..9f7769e6 100644
--- a/exec/coroipcs.c
+++ b/exec/coroipcs.c
@@ -99,12 +99,14 @@ struct zcb_mapped {
 	size_t size;
 };
 
+#if defined(_SEM_SEMUN_UNDEFINED) 
 union semun {
 	int val;
 	struct semid_ds *buf;
 	unsigned short int *array;
 	struct seminfo *__buf;
 };
+#endif
 
 enum conn_state {
 	CONN_STATE_THREAD_INACTIVE = 0,
diff --git a/lib/coroipcc.c b/lib/coroipcc.c
index 6d416089..c30fad7b 100644
--- a/lib/coroipcc.c
+++ b/lib/coroipcc.c
@@ -251,7 +251,7 @@ priv_change_send (struct ipc_instance *ipc_instance)
 	return (0);
 }
 
-#if !defined(semun)
+#if defined(_SEM_SEMUN_UNDEFINED)
 union semun {
         int val;
         struct semid_ds *buf;