diff --git a/include/xyzModem.h b/include/xyzModem.h
index 4ec10b5..f437bbd 100644
--- a/include/xyzModem.h
+++ b/include/xyzModem.h
@@ -97,7 +97,10 @@
 #endif
 } connection_info_t;
 
+#ifndef	BOOL_WAS_DEFINED
+#define BOOL_WAS_DEFINED
 typedef unsigned int bool;
+#endif
 
 #define false 0
 #define true 1