diff --git a/OBJECTS b/OBJECTS
new file mode 100644
index 0000000..23bfc66
--- /dev/null
+++ b/OBJECTS
@@ -0,0 +1,5 @@
+TARGET = main
+SRC = col.cpp hal.cpp main.cpp example.cpp
+
+SRCDIR = src
+INCDIR = inc
diff --git a/avr.Makefile b/avr.Makefile
index e88adf6..211e4e7 100644
--- a/avr.Makefile
+++ b/avr.Makefile
@@ -1,3 +1,5 @@
+include OBJECTS
+
 #==== Main Options =============================================================
 
 MCU = atmega328p
@@ -5,11 +7,7 @@ F_CPU = 16000000
 LFUSE = 0xf1
 HFUSE = 0xdf
 
-TARGET = main
-SRC = col.cpp hal.cpp main.cpp
 
-SRCDIR = src
-INCDIR = inc
 OBJDIR = build/avr
 BACKUPDIR = backup
 
diff --git a/linux.Makefile b/linux.Makefile
index cbf6f30..ca62658 100644
--- a/linux.Makefile
+++ b/linux.Makefile
@@ -1,10 +1,5 @@
+include OBJECTS
 
-TARGET = main
-
-SRC = col.cpp hal.cpp main.cpp
-
-SRCDIR = src
-INCDIR = inc
 OBJDIR = build/linux
 
 SRC_PATH = $(SRC:%=$(SRCDIR)/%)
@@ -18,6 +13,7 @@ CXXFLAGS += -std=c++17
 
 CFLAGS += -I$(INCDIR) -DLINUX
 CXXFLAGS += -I$(INCDIR) -DLINUX
+LDFLAGS += -lSDL2
 
 linux: $(OBJDIR)/$(TARGET)
 
@@ -28,7 +24,7 @@ all: $(OBJDIR)/$(TARGET)
 .PRECIOUS: $(OBJ)
 $(OBJDIR)/$(TARGET): $(OBJ) | $(OBJDIR)
 	@echo link $^
-	@$(CXX) -o $@ $^
+	@$(CXX) $(LDFLAGS) -o $@ $^
 	
 $(OBJDIR)/%.o: $(SRCDIR)/%.c  | $(OBJDIR)
 	@echo compile $<