Index: /issm/trunk/m4/issm_options.m4
===================================================================
--- /issm/trunk/m4/issm_options.m4	(revision 3938)
+++ /issm/trunk/m4/issm_options.m4	(revision 3939)
@@ -704,5 +704,5 @@
 	MULTITHREADINLIB=""
 	if test "$NUMTHREADS_VALUE" != "1"; then
-		MULTITHREADINGLIB="-lpthread"
+		MULTITHREADINGLIB="-lpthread -lrt"
 		AC_DEFINE([_MULTITHREADING_],[1],[with numthreads enabled])
 		AC_DEFINE_UNQUOTED([_NUMTHREADS_],[$NUMTHREADS_VALUE],[number of threads])