diff --git a/Makefile.include b/Makefile.include
index 0c2988548..e00c804d2 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -21,6 +21,15 @@ ifeq ($(DEFINES),)
   endif
 endif
 
+ifndef HOST_OS
+  ifeq ($(OS),Windows_NT)
+    $(warning Windows (NT) deteced.)
+    HOST_OS := Windows
+  else
+    HOST_OS := $(shell uname)
+  endif
+endif
+
 usage:
 	@echo "make MAKETARGETS... [TARGET=(TARGET)] [savetarget] [targets]"
 
diff --git a/cpu/avr/Makefile.avr b/cpu/avr/Makefile.avr
index 8a94b9eb0..611c8d1a1 100644
--- a/cpu/avr/Makefile.avr
+++ b/cpu/avr/Makefile.avr
@@ -1,15 +1,5 @@
 # $Id: Makefile.avr,v 1.27 2010/12/22 21:13:09 dak664 Exp $
 	
-### Check if we are running under Windows
-
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
-
 .SUFFIXES:
 
 ### Optimization setting. $make OPTI=0 for easier debugging of changed source file(s)
diff --git a/cpu/mc1322x/Makefile.mc1322x b/cpu/mc1322x/Makefile.mc1322x
index 389185b05..c0a95b009 100644
--- a/cpu/mc1322x/Makefile.mc1322x
+++ b/cpu/mc1322x/Makefile.mc1322x
@@ -72,8 +72,7 @@ CUSTOM_RULE_C_TO_O=yes
 CFLAGS += -I$(OBJECTDIR) -I$(CONTIKI_CPU)/board -DBOARD=$(TARGET)
 
 $(OBJECTDIR)/board.h: $(OBJECTDIR) 
-ifneq (,$(findstring Windows,$(OS)))
-	${info Cygwin detected.}
+ifeq ($(HOST_OS),Windows)
 	ln -f $(CONTIKI_CPU)/board/board.h $(OBJECTDIR)/board.h
 else
 	ln -sf ../$(CONTIKI_CPU)/board/board.h $(OBJECTDIR)/board.h
diff --git a/cpu/stm32w108/Makefile.stm32w108 b/cpu/stm32w108/Makefile.stm32w108
index 494de3a31..7eae06d4c 100644
--- a/cpu/stm32w108/Makefile.stm32w108
+++ b/cpu/stm32w108/Makefile.stm32w108
@@ -166,10 +166,8 @@ endif
 FLASHER = $(CONTIKI)/tools/stm32w/stm32w_flasher/stm32w_flasher
 
 # Check if we are running under Windows
-ifdef OS
-  ifneq (,$(findstring Windows,$(OS)))
-  	FLASHER = $(CONTIKI)/tools/stm32w/stm32w_flasher/stm32w_flasher.exe   
-  endif   
+ifeq ($(HOST_OS),Windows)
+  FLASHER = $(CONTIKI)/tools/stm32w/stm32w_flasher/stm32w_flasher.exe
 endif
 
 
diff --git a/doc/Makefile b/doc/Makefile
index 36f37491e..5e1591985 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -13,12 +13,12 @@ export doclatex	:= NO
 export docroot	:= ../
 
 # Get appropriate root for doxygen path cutoff
-ifneq (,$(findstring Windows,$(OS)))
-# on windows need to convert cygwin path to windows path for doxygen
-ifneq (,$(findstring cygdrive,$(pwd)))
-	cygroot	= $(subst /,$(space),$(patsubst /cygdrive/%,%,$(pwd)))
-	export docroot = $(firstword $(cygroot)):/$(subst $(space),/,$(wordlist 2,$(words $(cygroot)),$(cygroot)))
-endif
+ifeq ($(HOST_OS),Windows)
+  # on windows need to convert cygwin path to windows path for doxygen
+  ifneq (,$(findstring cygdrive,$(pwd)))
+    cygroot = $(subst /,$(space),$(patsubst /cygdrive/%,%,$(pwd)))
+    export docroot = $(firstword $(cygroot)):/$(subst $(space),/,$(wordlist 2,$(words $(cygroot)),$(cygroot)))
+  endif
 endif
 
 .PHONY: clean html pdf upload
diff --git a/platform/cooja/Makefile.cooja b/platform/cooja/Makefile.cooja
index 61c958735..e79fdbf1b 100644
--- a/platform/cooja/Makefile.cooja
+++ b/platform/cooja/Makefile.cooja
@@ -11,14 +11,6 @@ ifndef CONTIKI
   $(error CONTIKI not defined!)
 endif
 
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
-
 ### Assuming simulator quickstart if no JNI library name set from Cooja
 ifndef LIBNAME
 QUICKSTART=1
diff --git a/platform/esb/Makefile.esb b/platform/esb/Makefile.esb
index 91759f980..8aaf31edd 100644
--- a/platform/esb/Makefile.esb
+++ b/platform/esb/Makefile.esb
@@ -68,23 +68,15 @@ send:	$(CONTIKI)/tools/codeprop.c
 
 ### System dependent Makefile
 
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
-
-ifeq (${HOSTTYPE},FreeBSD)
+ifeq ($(HOST_OS),FreeBSD)
   # settings for FreeBSD
   -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.freebsd
 else
-ifndef WINDIR
-  # settings for unix
-  -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.unix
-else
-  # settings for windows
-  -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.win
-endif
+  ifeq ($(HOST_OS),Windows)
+    # settings for Windows
+    -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.win
+  else
+    # settings for an arbitary unix-like platform
+    -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.unix
+  endif
 endif
diff --git a/platform/iris/Makefile.iris b/platform/iris/Makefile.iris
index 8d58e24d5..d7ce508bb 100644
--- a/platform/iris/Makefile.iris
+++ b/platform/iris/Makefile.iris
@@ -31,23 +31,15 @@ include $(CONTIKIAVR)/Makefile.avr
 	avr-objdump -zhD $< > $@
 
 
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
-
 ifeq ($(PRGBOARD), )
   PRGBOARD = mib510
 endif
 
 ifeq ($(PORT), )
-  ifndef WINDIR
-    PORT = /dev/ttyUSB0 
-  else
+  ifeq ($(HOST_OS), Windows)
     PORT = COM1
+  else
+    PORT = /dev/ttyUSB0
   endif
 endif
 
diff --git a/platform/mb851/Makefile.mb851 b/platform/mb851/Makefile.mb851
index f1b127fde..ba3ac91a2 100644
--- a/platform/mb851/Makefile.mb851
+++ b/platform/mb851/Makefile.mb851
@@ -19,10 +19,8 @@ include $(CONTIKI)/cpu/stm32w108/Makefile.stm32w108
 
 SERIALDUMP = $(CONTIKI)/tools/stm32w/serialdump-linux
 
-ifdef OS
-  ifneq (,$(findstring Windows,$(OS)))
-    SERIALDUMP = $(CONTIKI)/tools/stm32w/serialdump-windows
-  endif
+ifeq ($(HOST_OS),Windows)
+  SERIALDUMP = $(CONTIKI)/tools/stm32w/serialdump-windows
 endif
 
 
diff --git a/platform/mbxxx/Makefile.mbxxx b/platform/mbxxx/Makefile.mbxxx
index e100e2991..6925a231f 100644
--- a/platform/mbxxx/Makefile.mbxxx
+++ b/platform/mbxxx/Makefile.mbxxx
@@ -18,10 +18,8 @@ include $(CONTIKI)/cpu/stm32w108/Makefile.stm32w108
 
 SERIALDUMP = $(CONTIKI)/tools/stm32w/serialdump-linux
 
-ifdef OS
-  ifneq (,$(findstring Windows,$(OS)))
-    SERIALDUMP = $(CONTIKI)/tools/stm32w/serialdump-windows
-  endif
+ifeq ($(HOST_OS),Windows)
+  SERIALDUMP = $(CONTIKI)/tools/stm32w/serialdump-windows
 endif
 
 
diff --git a/platform/micaz/Makefile.micaz b/platform/micaz/Makefile.micaz
index 021444e14..49499cf1a 100644
--- a/platform/micaz/Makefile.micaz
+++ b/platform/micaz/Makefile.micaz
@@ -26,23 +26,15 @@ include $(CONTIKIAVR)/Makefile.avr
 	avr-objdump -zhD $< > $@
 
 
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
-
 ifeq ($(PRGBOARD), )
   PRGBOARD = mib510
 endif
 
 ifeq ($(PORT), )
-  ifndef WINDIR
-    PORT = /dev/ttyS0 
-  else
+  ifeq ($(HOST_OS),Windows)
     PORT = COM1
+  else
+    PORT = /dev/ttyS0
   endif
 endif
 
diff --git a/platform/minimal-net/Makefile.minimal-net b/platform/minimal-net/Makefile.minimal-net
index 37e487cbc..dd35c8880 100644
--- a/platform/minimal-net/Makefile.minimal-net
+++ b/platform/minimal-net/Makefile.minimal-net
@@ -7,7 +7,7 @@ CONTIKI_TARGET_MAIN = ${addprefix $(OBJECTDIR)/,contiki-main.o}
 
 CONTIKI_TARGET_SOURCEFILES = contiki-main.c clock.c leds.c leds-arch.c cfs-posix.c cfs-posix-dir.c dlloader.c
 
-ifeq ($(OS),Windows_NT)
+ifeq ($(HOST_OS),Windows)
 CONTIKI_TARGET_SOURCEFILES += wpcap-drv.c wpcap.c
 else
 CONTIKI_TARGET_SOURCEFILES += tapdev-drv.c
@@ -21,7 +21,7 @@ endif
 
 CONTIKI_SOURCEFILES += $(CONTIKI_TARGET_SOURCEFILES)
 
-ifeq ($(OS),Windows_NT)
+ifeq ($(HOST_OS),Windows)
 TARGET_LIBFILES = /lib/w32api/libws2_32.a /lib/w32api/libiphlpapi.a
 endif
 
diff --git a/platform/msb430/Makefile.msb430 b/platform/msb430/Makefile.msb430
index f74ce49bf..af5c95caa 100644
--- a/platform/msb430/Makefile.msb430
+++ b/platform/msb430/Makefile.msb430
@@ -24,25 +24,17 @@ endif
 
 ### System dependent Makefile
 
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
-
-ifeq (${HOSTTYPE},FreeBSD)
+ifeq ($(HOST_OS),FreeBSD)
   # settings for FreeBSD
   -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.freebsd
 else
-ifndef WINDIR
-  # settings for unix
-  -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.unix
-else
-  # settings for windows
-  -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.win
-endif
+  ifeq ($(HOST_OS),Windows)
+    # settings for Windows
+    -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.win
+  else
+    # settings for an arbitary unix-like platform
+    -include $(CONTIKI)/platform/$(TARGET)/buildscripts/Makefile.unix
+  endif
 endif
 
 # If we are not running under Windows, we assume Linux
diff --git a/platform/native/Makefile.native b/platform/native/Makefile.native
index eade2e7a4..63ba12e9d 100644
--- a/platform/native/Makefile.native
+++ b/platform/native/Makefile.native
@@ -13,7 +13,7 @@ CONTIKI_TARGET_SOURCEFILES = contiki-main.c clock.c leds.c leds-arch.c \
                 button-sensor.c pir-sensor.c vib-sensor.c xmem.c \
                 sensors.c irq.c cfs-posix.c cfs-posix-dir.c
 
-ifeq ($(OS),Windows_NT)
+ifeq ($(HOST_OS),Windows)
 CONTIKI_TARGET_SOURCEFILES += wpcap-drv.c wpcap.c
 TARGET_LIBFILES = /lib/w32api/libws2_32.a /lib/w32api/libiphlpapi.a
 else
diff --git a/platform/sky/Makefile.common b/platform/sky/Makefile.common
index 066cad86b..e922d61c7 100644
--- a/platform/sky/Makefile.common
+++ b/platform/sky/Makefile.common
@@ -43,29 +43,27 @@ NUMPAR=20
 IHEXFILE=tmpimage.ihex
 
 # Check if we are running under Windows
-ifdef OS
-  ifneq (,$(findstring Windows,$(OS)))
-    USBDEVPREFIX=/dev/com
-    SERIALDUMP = $(CONTIKI)/tools/sky/serialdump-windows
-    MOTELIST = $(CONTIKI)/tools/sky/motelist-windows
-    TMOTE_BSL_FILE = tmote-bsl
-    TMOTE_BSL=$(if $(wildcard $(CONTIKI)/tools/sky/$(TMOTE_BSL_FILE).exe),1,0)
-    ifeq ($(TMOTE_BSL), 1)
-      NUMPAR = 1
-      BSL =  $(CONTIKI)/tools/sky/$(TMOTE_BSL_FILE)
-      MOTES = $(shell $(MOTELIST) | grep COM | \
-         cut -f 4 -d \  )
-    else
-      BSL = $(CONTIKI)/tools/sky/msp430-bsl-windows --telosb
-      BSL_FILETYPE = -I
-      MOTES = $(shell $(MOTELIST) | grep COM | \
-         cut -f 4 -d \  | \
-         perl -ne 'print $$1 - 1 . " " if(/COM(\d+)/);')
-    endif
-    CMOTES = $(shell $(MOTELIST) | grep COM | \
+
+  USBDEVPREFIX=/dev/com
+  SERIALDUMP = $(CONTIKI)/tools/sky/serialdump-windows
+  MOTELIST = $(CONTIKI)/tools/sky/motelist-windows
+  TMOTE_BSL_FILE = tmote-bsl
+  TMOTE_BSL=$(if $(wildcard $(CONTIKI)/tools/sky/$(TMOTE_BSL_FILE).exe),1,0)
+  ifeq ($(TMOTE_BSL), 1)
+    NUMPAR = 1
+    BSL =  $(CONTIKI)/tools/sky/$(TMOTE_BSL_FILE)
+    MOTES = $(shell $(MOTELIST) | grep COM | \
+       cut -f 4 -d \  )
+  else
+    BSL = $(CONTIKI)/tools/sky/msp430-bsl-windows --telosb
+    BSL_FILETYPE = -I
+    MOTES = $(shell $(MOTELIST) | grep COM | \
        cut -f 4 -d \  | \
-       perl -ne 'print $$1 . " " if(/COM(\d+)/);')
+       perl -ne 'print $$1 - 1 . " " if(/COM(\d+)/);')
   endif
+  CMOTES = $(shell $(MOTELIST) | grep COM | \
+     cut -f 4 -d \  | \
+     perl -ne 'print $$1 . " " if(/COM(\d+)/);')
 endif
 
 # If we are not running under Windows, we assume Linux
diff --git a/platform/stepper-robot/Makefile.stepper-robot b/platform/stepper-robot/Makefile.stepper-robot
index 6ad4065c8..b74e6180d 100644
--- a/platform/stepper-robot/Makefile.stepper-robot
+++ b/platform/stepper-robot/Makefile.stepper-robot
@@ -27,12 +27,3 @@ ifndef BASE_IP
 BASE_IP := 172.16.1.1
 endif
 
-### System dependent Makefile
-
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif
diff --git a/platform/stm32test/Makefile.stm32test b/platform/stm32test/Makefile.stm32test
index 8f003a200..4c7cf90c9 100644
--- a/platform/stm32test/Makefile.stm32test
+++ b/platform/stm32test/Makefile.stm32test
@@ -24,12 +24,3 @@ ifndef BASE_IP
 BASE_IP := 172.16.1.1
 endif
 
-### System dependent Makefile
-
-ifndef WINDIR
-  ifdef OS
-    ifneq (,$(findstring Windows,$(OS)))
-      WINDIR := Windows
-    endif
-  endif
-endif