diff --git a/CMake/unix-cache.cmake b/CMake/unix-cache.cmake
index e8a7df1cbc..8ecd206186 100644
--- a/CMake/unix-cache.cmake
+++ b/CMake/unix-cache.cmake
@@ -194,9 +194,12 @@ if(APPLE OR
    CYGWIN)
   set(HAVE_PIPE2 0)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR
+       BSD OR
+       CMAKE_SYSTEM_NAME STREQUAL "DragonFlyBSD" OR
        CMAKE_SYSTEM_NAME STREQUAL "FreeBSD" OR
        CMAKE_SYSTEM_NAME STREQUAL "NetBSD" OR
-       CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
+       CMAKE_SYSTEM_NAME STREQUAL "OpenBSD" OR
+       CMAKE_SYSTEM_NAME STREQUAL "SunOS")
   set(HAVE_PIPE2 1)
 endif()
 set(HAVE_POLL 1)