diff --git a/lib/lib_audio/ESP8266Audio/src/AudioFileSourceICYStream.cpp b/lib/lib_audio/ESP8266Audio/src/AudioFileSourceICYStream.cpp
index 63c84f328..bbc348d53 100644
--- a/lib/lib_audio/ESP8266Audio/src/AudioFileSourceICYStream.cpp
+++ b/lib/lib_audio/ESP8266Audio/src/AudioFileSourceICYStream.cpp
@@ -20,7 +20,9 @@
 
 #if defined(ESP32) || defined(ESP8266)
 
-#define _GNU_SOURCE
+#ifndef _GNU_SOURCE
+  #define _GNU_SOURCE
+#endif
 
 #include "AudioFileSourceICYStream.h"
 #include <string.h>
diff --git a/lib/lib_audio/ESP8266Audio/src/libflac/config.h b/lib/lib_audio/ESP8266Audio/src/libflac/config.h
index cf6c07dfe..b0aebe44d 100644
--- a/lib/lib_audio/ESP8266Audio/src/libflac/config.h
+++ b/lib/lib_audio/ESP8266Audio/src/libflac/config.h
@@ -3,7 +3,9 @@
 #ifdef DEBUG
   #undef NDEBUG
 #else
-  #define NDEBUG
+  #ifndef NDEBUG
+    #define NDEBUG
+  #endif
 #endif
 
 /* config.h.  Generated from config.h.in by configure.  */