diff --git a/src/BuildOpt.h b/src/BuildOpt.h
index d64f50061..29be4d8ae 100644
--- a/src/BuildOpt.h
+++ b/src/BuildOpt.h
@@ -29,7 +29,11 @@
 // set which output port should be used for debug output
 // may be Serial port (on Arduino) or file like stdout or stderr (on generic platforms)
 #if !defined(RADIOLIB_DEBUG_PORT)
-  #define RADIOLIB_DEBUG_PORT   Serial
+  #if ARDUINO >= 100
+    #define RADIOLIB_DEBUG_PORT   Serial
+  #else
+    #define RADIOLIB_DEBUG_PORT   stdout
+  #endif
 #endif
 
 /*
@@ -433,10 +437,6 @@
   #define RADIOLIB_NONVOLATILE_READ_DWORD(addr)       (*((uint32_t *)(void *)(addr)))
   #define RADIOLIB_TYPE_ALIAS(type, alias)            using alias = type;
 
-  #if !defined(RADIOLIB_DEBUG_PORT)
-    #define RADIOLIB_DEBUG_PORT                       stdout
-  #endif
-
   #define DEC 10
   #define HEX 16
   #define OCT 8