diff --git a/serial_io.cpp b/serial_io.cpp
index 89effa0..34e57a6 100644
--- a/serial_io.cpp
+++ b/serial_io.cpp
@@ -87,7 +87,7 @@ int serialport_set_config(int fd, int baud)
     return 0;
 }
 
-int serialport_init(const char* device, int baud, bool block = false)
+int serialport_init(const char* device, int baud, bool block)
 {
     int fd;
     fd = open(device, O_RDWR | O_NOCTTY | (block ? 0 : O_NONBLOCK));
diff --git a/serial_io.h b/serial_io.h
index 1daa375..844e74e 100644
--- a/serial_io.h
+++ b/serial_io.h
@@ -22,7 +22,7 @@ void printRates();
 
 int serialport_set_config(int fd, int baud);
 
-int serialport_init(const char* device, int baud = BAUDRATE);
+int serialport_init(const char* device, int baud = BAUDRATE, bool block = false);
 
 
 #endif // SERIAL_H