diff --git a/src/butterfly.h b/src/butterfly.h
index 3ba48dfe..9bfc30bc 100644
--- a/src/butterfly.h
+++ b/src/butterfly.h
@@ -23,13 +23,13 @@
 extern "C" {
 #endif
 
-extern const char butterfly_desc[];
-extern const char butterfly_mk_desc[];
-void butterfly_initpgm(PROGRAMMER *pgm);
-void butterfly_mk_initpgm(PROGRAMMER *pgm);
+  extern const char butterfly_desc[];
+  extern const char butterfly_mk_desc[];
+  void butterfly_initpgm(PROGRAMMER *pgm);
+  void butterfly_mk_initpgm(PROGRAMMER *pgm);
 
 #ifdef __cplusplus
 }
 #endif
 
-#endif /* butterfly_h */
+#endif