diff --git a/lib/process_shared/posix/semaphore.rb b/lib/process_shared/posix/semaphore.rb
index fab29f8..d1fe59e 100644
--- a/lib/process_shared/posix/semaphore.rb
+++ b/lib/process_shared/posix/semaphore.rb
@@ -28,7 +28,10 @@ module ProcessShared
         attach_function :sem_post, [:sem_p], :int
         attach_function :sem_wait, [:sem_p], :int, :blocking => true
         attach_function :sem_trywait, [:sem_p], :int, :blocking => true
-        attach_function :sem_timedwait, [:sem_p, TimeSpec], :int, :blocking => true
+
+        # Workaround bug which only appears to affect Ruby 1.8.7 and REE
+        BLOCKING_SEM_TIMEDWAIT = (RUBY_VERSION != '1.8.7')
+        attach_function :sem_timedwait, [:sem_p, TimeSpec], :int, :blocking => BLOCKING_SEM_TIMEDWAIT
 
         error_check(:sem_close, :sem_unlink, :sem_init, :sem_destroy,
                     :sem_getvalue, :sem_post, :sem_wait, :sem_trywait,