diff --git a/objectstore/BackendRados.cpp b/objectstore/BackendRados.cpp
index 0f2e51df8b6bbf96f4660a019057c1346aa07c37..3c1871140dcf5bcfb057663cf15d40837025d8e4 100644
--- a/objectstore/BackendRados.cpp
+++ b/objectstore/BackendRados.cpp
@@ -3,6 +3,7 @@
 #include <rados/librados.hpp>
 #include <sys/syscall.h>
 #include <errno.h>
+#include <unistd.h>
 
 namespace cta { namespace objectstore {
 
@@ -159,4 +160,4 @@ BackendRados::Parameters* BackendRados::getParams() {
   return ret.release();
 }
 
-}}
\ No newline at end of file
+}}