diff --git a/Makefile b/Makefile
index 7b5327e..a368d0c 100644
--- a/Makefile
+++ b/Makefile
@@ -11,3 +11,7 @@ avr:
 
 flash:
 	@make -f avr.Makefile flash
+
+clean:
+	@rm -r build
+	@echo clean all
diff --git a/avr.Makefile b/avr.Makefile
index 69cfaa4..e88adf6 100644
--- a/avr.Makefile
+++ b/avr.Makefile
@@ -171,18 +171,16 @@ $(OBJDIR)/%.lss: $(OBJDIR)/%.elf
 
 .SECONDARY: $(TARGET).elf
 .PRECIOUS: $(OBJ)
-$(OBJDIR)/%.elf: $(OBJ)
+$(OBJDIR)/%.elf: $(OBJ) | $(OBJDIR)
 	@echo link $^
 	@$(CXX) $(CPU) $^ -o $@ $(LDFLAGS) #-lstdc++
 
 
-$(OBJDIR)/%.o: $(SRCDIR)/%.c
-	@$(shell mkdir -p $(OBJDIR) 2>/dev/null)
+$(OBJDIR)/%.o: $(SRCDIR)/%.c | $(OBJDIR)
 	@echo compile $<
 	@$(CC) -c $(CPU) $(CFLAGS) $< -o $@
 
-$(OBJDIR)/%.o: $(SRCDIR)/%.cpp
-	@$(shell mkdir -p $(OBJDIR) 2>/dev/null)
+$(OBJDIR)/%.o: $(SRCDIR)/%.cpp | $(OBJDIR)
 	@echo compile $<
 	@$(CXX) -c $(CPU) $(CXXFLAGS) $< -o $@
 
@@ -190,15 +188,12 @@ $(OBJDIR)/%.o: $(SRCDIR)/%.cpp
 $(OBJDIR)/%.size: $(OBJDIR)/%.elf
 	@$(AVRSIZE) -A $< | tee $@
 
+$(OBJDIR):
+	mkdir -p $(OBJDIR)
 
 clean:
-	@$(REMOVE) "size"
-	@$(REMOVE) "$(TARGET).hex"
-	@$(REMOVE) "$(TARGET).eep"
-	@$(REMOVE) "$(TARGET).elf"
-	@$(REMOVE) "$(TARGET).lss"
 	@$(REMOVEDIR) "$(OBJDIR)"
-	@echo clean $(TARGET)
+	@echo clean $(OBJDIR)
 
 
 backup:
diff --git a/linux.Makefile b/linux.Makefile
index 908d973..cbf6f30 100644
--- a/linux.Makefile
+++ b/linux.Makefile
@@ -10,6 +10,7 @@ OBJDIR = build/linux
 SRC_PATH = $(SRC:%=$(SRCDIR)/%)
 OBJ = $(SRC_PATH:$(SRCDIR)/%.cpp=$(OBJDIR)/%.o)
 
+REMOVEDIR = rm -rf
 
 CFLAGS += -std=gnu99
 CXXFLAGS += -std=c++17
@@ -26,6 +27,7 @@ all: $(OBJDIR)/$(TARGET)
 .SECONDARY: $(TARGET)
 .PRECIOUS: $(OBJ)
 $(OBJDIR)/$(TARGET): $(OBJ) | $(OBJDIR)
+	@echo link $^
 	@$(CXX) -o $@ $^
 	
 $(OBJDIR)/%.o: $(SRCDIR)/%.c  | $(OBJDIR)
@@ -36,6 +38,9 @@ $(OBJDIR)/%.o: $(SRCDIR)/%.cpp | $(OBJDIR)
 	@echo compile $<
 	@$(CXX) -c $(CXXFLAGS) $< -o $@
 
-
 $(OBJDIR):
 	mkdir -p $(OBJDIR)
+
+clean:
+	@$(REMOVEDIR) "$(OBJDIR)"
+	@echo clean $(OBJDIR)