diff --git a/src/OpenMesh/Tools/Utils/getopt.h b/src/OpenMesh/Tools/Utils/getopt.h
index df0d7e01..a156402e 100644
--- a/src/OpenMesh/Tools/Utils/getopt.h
+++ b/src/OpenMesh/Tools/Utils/getopt.h
@@ -5,23 +5,26 @@
 #include <OpenMesh/Core/System/OpenMeshDLLMacros.hh>
 
 #if defined(WIN32)
-#if   defined(__cplusplus)
+ #if   defined(__cplusplus)
+ 
+  extern "C" {
+ 
+   extern OPENMESHDLLEXPORT int opterr;
+   extern OPENMESHDLLEXPORT int optind;
+   extern OPENMESHDLLEXPORT int optopt;
+   extern OPENMESHDLLEXPORT int optreset;
+   extern OPENMESHDLLEXPORT char  *optarg;
 
-extern "C" {
+   OPENMESHDLLEXPORT extern int getopt(int nargc, char * const *nargv, const char *ostr);
 
-extern OPENMESHDLLEXPORT int opterr;
-extern OPENMESHDLLEXPORT int optind;
-extern OPENMESHDLLEXPORT int optopt;
-extern OPENMESHDLLEXPORT int optreset;
-extern OPENMESHDLLEXPORT char  *optarg;
+  }
 
-OPENMESHDLLEXPORT extern int getopt(int nargc, char * const *nargv, const char *ostr);
+  #endif
 
-}
-
-#  endif
+#elif defined __APPLE__
+ #include <unistd.h>
 #else
-#  include <getopt.h>
+ #include <getopt.h>
 #endif
 
 #endif /* _GETOPT_H_ */