diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7e3f2ab8f..9fc4f5675 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -181,7 +181,7 @@ ELSEIF(MINGW)
     add_definitions(-D_WIN32_WINNT=0x0600)
 ELSEIF(WIN32)
     set(PLATFORM_LIBRARIES winmm ws2_32)
-ELSE()
+ELSEIF(CMAKE_SYSTEM_NAME MATCHES "^(Linux|kFreeBSD|GNU|SunOS)$")
     set(PLATFORM_LIBRARIES rt)
 ENDIF (APPLE)