diff --git a/DDG4/plugins/Geant4DetectorConstructionResources.cpp b/DDG4/plugins/Geant4DetectorConstructionResources.cpp
index f07c283a5..f6aed44e5 100644
--- a/DDG4/plugins/Geant4DetectorConstructionResources.cpp
+++ b/DDG4/plugins/Geant4DetectorConstructionResources.cpp
@@ -14,6 +14,7 @@
 
 // Framework include files
 #include <DDG4/Geant4DetectorConstruction.h>
+#include <unistd.h>
 
 // C/C++ include files