diff --git a/apps/Makefile b/apps/Makefile
index 88fd32bafd..ecac408a85 100644
--- a/apps/Makefile
+++ b/apps/Makefile
@@ -19,8 +19,9 @@ FIRMWARE := ../firmware
 
 INCLUDES= -I$(FIRMWARE)/include -I$(FIRMWARE) -I$(FIRMWARE)/common -I$(FIRMWARE)/drivers -I$(FIRMWARE)/malloc -I. -I$(OBJDIR)
 
-# store output files in this directory:
-OBJDIR = .
+ifndef OBJDIR
+	"Don't run make in the apps dir!"
+endif
 
 CFLAGS = -O -W -Wall -m1 -nostdlib -ffreestanding -Wstrict-prototypes -fomit-frame-pointer -fschedule-insns $(INCLUDES) $(TARGET) $(DEFINES) -DAPPSVERSION=\"$(VERSION)\" $(EXTRA_DEFINES)
 AFLAGS += -small -relax
diff --git a/firmware/Makefile b/firmware/Makefile
index 6a9aca303d..98507d979c 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -15,8 +15,10 @@ OC    = sh-elf-objcopy
 
 INCLUDES=-Iinclude -I. -Icommon -Idrivers
 
-# store output files in this directory:
-OBJDIR = .
+ifndef OBJDIR
+	"Don't run make in the firmware dir!"
+endif
+
 TOOLSDIR = ../tools
 
 CFLAGS = -W -Wall -O -m1 -nostdlib -ffreestanding -Wstrict-prototypes $(INCLUDES) $(TARGET) $(EXTRA_DEFINES)