--- a/Makefile
+++ b/Makefile
@@ -129,10 +129,8 @@
 # --------------------------------------------------------------------
 #                                             Auto-detect architecture
 # --------------------------------------------------------------------
-MINGW32_NT-6.1_i386_ARCH := mingw32
-MINGW32_NT-6.1_x86_64_ARCH := mingw32
-MINGW64_NT-6.1_i386_ARCH := mingw64
-MINGW64_NT-6.1_x86_64_ARCH := mingw64
+MINGW32_ARCH := mingw32
+MINGW64_ARCH := mingw64
 Darwin_PPC_ARCH := mac
 Darwin_Power_Macintosh_ARCH := mac
 Darwin_i386_ARCH := maci64
@@ -143,7 +141,7 @@
 Linux_x86_64_ARCH := glnxa64
 
 UNAME := $(shell uname -sm)
-ARCH ?= $($(shell echo "$(UNAME)" | tr \  _)_ARCH)
+ARCH ?= $($(shell uname | sed -e 's/_.*//')_ARCH)
 
 # sanity check
 ifeq ($(ARCH),)