-# We therefore use a /cygdrive path if we are on cygwin
-ifeq '$(shell cygpath "c:/" 2> /dev/null)' ''
-MK_INSTALL_DEST = $1
+# We therefore use a /cygdrive path if we are on cygwin (only)
+# (This will make a Cygwin build run slowly
+# because of all those shell invocations.)
+ifeq "$(OSTYPE)" "cygwin"
+MK_INSTALL_DEST = $$(cygpath $1)