diff --git a/README.md b/README.md
index 8ba07bc..819eff0 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ On the Mac you might want to set:
 On Linux, you might prefer:
 
     ARDUINO_DIR   = /usr/share/arduino
-    ARDMK_DIR     = /usr/local
+    ARDMK_DIR     = /usr
     AVR_TOOLS_DIR = /usr
 
 The Makefile also delegates resetting the board to a short Perl program.
diff --git a/arduino-mk/Arduino.mk b/arduino-mk/Arduino.mk
index b0fb653..17fb167 100644
--- a/arduino-mk/Arduino.mk
+++ b/arduino-mk/Arduino.mk
@@ -53,7 +53,7 @@
 # On Linux, you might prefer:
 #
 #   ARDUINO_DIR   = /usr/share/arduino
-#   ARDMK_DIR     = /usr/local
+#   ARDMK_DIR     = /usr
 #   AVR_TOOLS_DIR = /usr
 #
 # You can either set these up in the Makefile, or put them in your
@@ -88,7 +88,7 @@
 #       BOARD_TAG    = uno
 #       MONITOR_PORT = /dev/cu.usb*
 #
-#       include /usr/local/share/Arduino.mk
+#       include /usr/share/arduino/Arduino.mk
 #
 # Hopefully these will be self-explanatory but in case they're not:
 #
@@ -236,7 +236,15 @@ else
     echo $(error "ARDMK_DIR is not defined")
 endif
 
-include $(ARDMK_DIR)/arduino-mk/Common.mk
+ifneq ($(wildcard $(ARDMK_DIR)/arduino-mk/Common.mk),)
+    # git checkout
+    include $(ARDMK_DIR)/arduino-mk/Common.mk
+else
+    ifneq ($(wildcard $(ARDMK_DIR)/Common.mk),) 
+        # package install
+        include $(ARDMK_DIR)/Common.mk
+    endif
+endif
 
 ########################################################################
 #
diff --git a/arduino-mk/chipKIT.mk b/arduino-mk/chipKIT.mk
index ffcdf1b..874b65e 100644
--- a/arduino-mk/chipKIT.mk
+++ b/arduino-mk/chipKIT.mk
@@ -39,7 +39,15 @@ else
     echo $(error "ARDMK_DIR is not defined")
 endif
 
-include $(ARDMK_DIR)/arduino-mk/Common.mk
+ifneq ($(wildcard $(ARDMK_DIR)/arduino-mk/Common.mk),)
+    # git checkout
+    include $(ARDMK_DIR)/arduino-mk/Common.mk
+else
+    ifneq ($(wildcard $(ARDMK_DIR)/Common.mk),) 
+        # package install
+        include $(ARDMK_DIR)/Common.mk
+    endif
+endif
 
 ifndef MPIDE_DIR
     AUTO_MPIDE_DIR := $(firstword \