From https://github.com/darkk/redsocks/pull/105

commit d5cabecb6a8369fb2bd883b43205035dd87187a5
Author: a7ypically <a7ypically@gmail.com>
Date:   Sat Jun 3 21:33:20 2017 +0300

    Update Makefile

--- a/Makefile
+++ b/Makefile
@@ -26,11 +26,11 @@ tags: *.c *.h
 	ctags -R
 
 $(CONF):
-	@case `uname` in \
-	Linux*) \
+	@case `$(CC) -dumpmachine` in \
+	*linux*) \
 		echo "#define USE_IPTABLES" >$(CONF) \
 		;; \
-	OpenBSD) \
+	*openbsd*) \
 		echo "#define USE_PF" >$(CONF) \
 		;; \
 	*) \
@@ -66,7 +66,7 @@ gen/.build:
 base.c: $(CONF)
 
 $(DEPS): $(SRCS)
-	gcc -MM $(SRCS) 2>/dev/null >$(DEPS) || \
+	$(CC) -MM $(SRCS) 2>/dev/null >$(DEPS) || \
 	( \
 		for I in $(wildcard *.h); do \
 			export $${I//[-.]/_}_DEPS="`sed '/^\#[ \t]*include \?"\(.*\)".*/!d;s//\1/' $$I`"; \