diff --git a/firmware/common/dir.h b/firmware/common/dir.h
index 7f37d08cf5..e03d50901c 100644
--- a/firmware/common/dir.h
+++ b/firmware/common/dir.h
@@ -57,9 +57,13 @@ typedef struct DIRtag
 #endif //   WIN32
 #endif // SIMULATOR
 
+#ifndef DIRFUNCTIONS_DEFINED
+
 extern DIR* opendir(char* name);
 extern int closedir(DIR* dir);
 
 extern struct dirent* readdir(DIR* dir);
 
+#endif /* DIRFUNCTIONS_DEFINED */
+
 #endif