--- a/configure.ac	2019-04-05 10:27:19.026197625 +0200
+++ b/configure.ac	2019-04-05 10:28:10.187291374 +0200
@@ -133,7 +133,7 @@
 # Solaris needs -lsocket, -lnsl and -lrt
 AC_SEARCH_LIBS([gethostbyname], [nsl])
 AC_SEARCH_LIBS([getsockopt], [socket])
-AC_SEARCH_LIBS([sem_wait], [rt])
+AC_SEARCH_LIBS([sem_wait], [rt] [pthread])
 
 # Check for X and Motif headers and libraries
 AC_PATH_X