diff --git a/project/Core/Inc/modbus-tcp.h b/project/Core/Inc/modbus-tcp.h
index 22b60a2..0e1f289 100644
--- a/project/Core/Inc/modbus-tcp.h
+++ b/project/Core/Inc/modbus-tcp.h
@@ -11,6 +11,7 @@
 
 
 #include <tcp.h>
+#include <string.h>
 
 void modbus_init( void );