--- openal-soft-1.16.0/CMakeLists.txt-opch	   :: 
+++ openal-soft-1.16.0/CMakeLists.txt	   :: 
@@ -62,8 +62,9 @@
     SET(LIBNAME openal)
 
     # These are needed on non-Windows systems for extra features
-    ADD_DEFINITIONS(-D_GNU_SOURCE=1 -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700)
-    SET(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -D_GNU_SOURCE=1 -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700")
+    # Old Solaris and illumos versions only know about 200112L and 600
+    ADD_DEFINITIONS(-D_GNU_SOURCE=1 -D_POSIX_C_SOURCE=200112L -D_XOPEN_SOURCE=600)
+    SET(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -D_GNU_SOURCE=1 -D_POSIX_C_SOURCE=200112L -D_XOPEN_SOURCE=600")
 ENDIF()
 
 # Set defines for large file support