diff --git a/Makefile b/Makefile
index 0c44b20..5ba8446 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,8 @@ TARGET = ArduinoIO
 # The C source files
 SRC = 
 # The C++ source files
-PSRC += main.cpp $(wildcard helper/*.cpp) 
+PSRC += main.cpp
+PSRC += $(wildcard helper/*.cpp) 
 PSRC += arduino_core/ArduinoCore-avr/libraries/SPI/src/SPI.cpp
 # extra Arduino libraries
 ARDLIBS =