--- a/gnuradio-core/src/lib/CMakeLists.txt
+++ b/gnuradio-core/src/lib/CMakeLists.txt
@@ -70,7 +70,7 @@
 endif()
 
 #need to link with librt on ubuntu 11.10 for shm_*
-if(LINUX)
+if((LINUX) OR (CMAKE_SYSTEM_NAME STREQUAL "kFreeBSD"))
     list(APPEND gnuradio_core_libs rt)
 endif()
 
