diff --git a/.gitignore b/.gitignore
index 995d637..3760b3b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 doc/build
+linux/build/obj
diff --git a/linux/build/Makefile b/linux/build/Makefile
index 1e00b1a..31df0ca 100644
--- a/linux/build/Makefile
+++ b/linux/build/Makefile
@@ -49,8 +49,8 @@ endif
 CPPFLAGS_G = $(CFLAGS_G) -std=c++0x -Wnon-virtual-dtor
 LDFLAGS_G = 
 
-COMMON_DIR = ../../common
-SRC_DIR = ../src
+COMMON_DIR = $(abspath ../../common)
+SRC_DIR = $(abspath ../src)
 OBJ_DIR = obj
 
 OBJ_FILES = $(OBJ_DIR)/ptp_message.o\