--- a/src/lib/daemon.c
+++ b/src/lib/daemon.c
@@ -40,7 +40,9 @@
 #include <string.h>
 #include <sys/types.h>
 // some linux are picky
-#define __USE_GNU
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
 #include <unistd.h>
 
 #include "util.h"
@@ -151,4 +153,4 @@ void SetPriv(char *userid, char *groupid
         }
     }
 
-}  // End of SetPriv
\ No newline at end of file
+}  // End of SetPriv
--- a/src/nfreplay/nfreplay.c
+++ b/src/nfreplay/nfreplay.c
@@ -73,8 +73,7 @@
 #undef FPURGE
 #ifdef HAVE___FPURGE
 #define FPURGE __fpurge
-#endif
-#ifdef HAVE_FPURGE
+#elif defined(HAVE_FPURGE)
 #define FPURGE fpurge
 #endif